Ignition question involving use of ballast resistor
From : jack
Q: 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. could it be because the high voltage is leaking out to ground somewhere on the way to the plugs i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
Replies:
From : Annonymous
rotflmao !!! .
From : scott dorsey
hls nospam@nospam.nix wrote low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. i suspect the pure resistance is less of a factor than the distributed impedance wouldnt you imagine i am not really sure... i think you can look at the cable as a lumped-sum anyway. its pretty much just the resistance of the cable that will affect how much the coil will ring on the tail end of the pulse and i think that is the big deal. the capacitance between the cable conductors and ground could make a difference but they are going to be different in every installation depending on how the cables are laid out. the series inductance of the cable should be minimal. --scott -- cest un nagra. cest suisse et tres tres precis. .
From : bill putney
scott dorsey wrote hls nospam@nospam.nix wrote low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. i suspect the pure resistance is less of a factor than the distributed impedance wouldnt you imagine i am not really sure... i think you can look at the cable as a lumped-sum anyway. its pretty much just the resistance of the cable that will affect how much the coil will ring on the tail end of the pulse and i think that is the big deal. the capacitance between the cable conductors and ground could make a difference but they are going to be different in every installation depending on how the cables are laid out. the series inductance of the cable should be minimal. --scott i think the whole idea behind the msw magneto-suppressive spiral wound solid wire wires was to reduce the d.c. resistance relative to resistive core wires - a thing of the past for increased spark current but increased inductance to keep the emi/rfi radio interferenece within reasonable limits - kind of the best of both worlds hotter spark low radio interference. -- bill putney to reply by e-mail replace the last letter of the alphabet in my address with the letter x .
From : steve lusardi
jack the purpose of a ballast resister is to allow a lower voltage ignition coil to be used. the reason for this is that when the starter motor is engaged battery voltage will drop to say 8 v. you will note that when wired correctly the ballast resister is bypassed at that time allowing the coil to create adequate spark during lower battery voltage conditions . when the starter is then disengaged the resister bypass is also dropped and the resister is now in play to reduce excessive heating of the coil. electronic ignitions are very sensitive to coil configurations as they provide coil drive and can be permanently damaged if the dc resistance of the coil is too low. follow the manufacturers recommendations. steve 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. could it be because the high voltage is leaking out to ground somewhere on the way to the plugs i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
From : jim sjedgingn0sp
jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. normally when all is working as it should what limits voltage is the sparkplug gap and the engine compression actually the absolute pressure inside the cylinder. a wider gap or more pressure will cause the voltage to climb higher before it will cross the gap. acceleration from a stop often will produce the greatest pressure inside the cylinder. could it be because the high voltage is leaking out to ground somewhere on the way to the plugs yes it could be that - if the voltage climbs too high too fast it finds another path instead of the spark plug gap. ultimately your ballast resister doesnt limit the voltage at the spark plug but it does slow down the rise in voltage which means that some other points in the secondary wont get quite as high. if stray arcing in the secondary is what is happening it would be likely that it would get progressively worse over time as the stray arcs develops a carbon trail that the current can follow more easily. the cause could also be in the primary there may be something that saturates in the primary or even something intended to limit voltage/current to protect against damage. -jim i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
From : hls
normally when all is working as it should what limits voltage is the spark plug gap and the engine compression actually the absolute pressure inside the cylinder. a wider gap or more pressure will cause the voltage to climb higher before it will cross the gap. acceleration from a stop often will produce the greatest pressure inside the cylinder. this was especially true when the kettering system was used. when capacitive discharged systems came along it pretty much stopped being true. their rise times are so short and transformer action so definite that they usually put up much more constant ignition performance. i dont know what the multiple spark discharge systems do. are they cd or something else some early studies showed that all things being equal a small single spark ignited the fuel as well as anything else. some university studies in england showed that high performance ignition systems which gave significant gains were possible but they were not necessarily simple and cheap either. it is my opinion and nothing more that there is little to be gained from systems like the msd for normal driving. for racing maybe.... .
From : Annonymous
i would suspect that too much primary current just supersaturates the coil and it doesnt discharge properly inhibiting the next charge/ discharge cycle. dan .
From : hls
low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. i suspect the pure resistance is less of a factor than the distributed impedance wouldnt you imagine .
From : scott dorsey
jack jack@thewildkingdom.com wrote from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the ballast resistor does more than just change the voltage it can change the shape of the pulse through the coil as well. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. no using a wire with a lower resistance will slightly increase the voltage to the plug. but honestly the difference is very small because the voltage is so high and current so low that it takes a lot of resistance to cause much drop. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. what you want is an ignition system analyzer that will let you look at the signal coming out of the coil on a crt. this will tell you what is really happening when you put the ballast resistor in. ask older shops around town if they still have an analyzer kicking around. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. the scope will tell you and without the scope you have no real chance of seeing what is happening. --scott -- cest un nagra. cest suisse et tres tres precis. .
From : jim sjedgingn0sp
hls wrote normally when all is working as it should what limits voltage is the spark plug gap and the engine compression actually the absolute pressure inside the cylinder. a wider gap or more pressure will cause the voltage to climb higher before it will cross the gap. acceleration from a stop often will produce the greatest pressure inside the cylinder. this was especially true when the kettering system was used. when capacitive discharged systems came along it pretty much stopped being true. what stopped being true the statement you are responding to has never stopped being true. it may have become unimportant to know that it is true but that is hardly the same as being not true.. their rise times are so short and transformer action so definite that they usually put up much more constant ignition performance. how does this information relate to solving the ops problem the rate at which voltage is developed in the coil is going to be a function of resistance and inductance no matter what. which is why changing resistance produces different results. i dont know what the multiple spark discharge systems do. are they cd or something else some early studies showed that all things being equal a small single spark ignited the fuel as well as anything else. some university studies in england showed that high performance ignition systems which gave significant gains were possible but they were not necessarily simple and cheap either. it is my opinion and nothing more that there is little to be gained from systems like the msd for normal driving. for racing maybe.... his intent is related to neither of those - it is to improve emissions. -jim .
From : Annonymous
jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. im going to say msd designed the output section of their ignition system wrong and maybe when the resistance is low it goes into current-limiting mode to protect itself. another possibility is the high voltage protection for the output section typically some zener diodes and capacitor is interacting badly with the coil primary. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. high voltage leakage shouldnt be a problem with modern 1980s and later distributor caps rotors and wires. on the other hand after i installed a cd ignition in my 1975 dodge dart 2 caps cracked in a few months. a slight modification to limit the primary voltage to under 400v stopped this. .
From : Annonymous
hls wrote i dont know what the multiple spark discharge systems do. are they cd or something else theyre usually ordinary flyback systems just like points systems. i never saw a cd multistrike system but that was long ago when every cd system was triggered by an scr a device that can be turned on but not turned off. but since then high voltage high current devices that can be turned off have become more common so multistrike cd should be easier to implement. i had a double-strike cd system that consisted of 2 separate cd units because i didnt know how to make anything better. it is my opinion and nothing more that there is little to be gained from systems like the msd for normal driving. for racing maybe.... true thanks to the epa and its stringent emissions standards that include cold weather cold engine conditions. .
From : jack
steve lusardi wrote jack the purpose of a ballast resister is to allow a lower voltage ignition coil to be used. the reason for this is that when the starter motor is engaged battery voltage will drop to say 8 v. you will note that when wired correctly the ballast resister is bypassed at that time allowing the coil to create adequate spark during lower battery voltage conditions . when the starter is then disengaged the resister bypass is also dropped and the resister is now in play to reduce excessive heating of the coil. electronic ignitions are very sensitive to coil configurations as they provide coil drive and can be permanently damaged if the dc resistance of the coil is too low. follow the manufacturers recommendations. steve steve thanks for the heads up on the wiring. i didnt run the b+ wire to the coil from the starter relay because i felt that the msd ignition and msd coil together would provide enough spark going through the ballast resistor even with the engine cranking. it proved to be true. the engine starts up immediately with the 12+ volts from the ignition switch going to the coil through the ballast resistor. i was mainly intent at the time to test the idea that the stumble problem was being caused by trying to push too high a voltage to the plug gap. the ballast resistor was my way of reducing the voltage at the plug gap while using both the msd coil and ignition together. the ballast resistor is rated at 1 ohm and measures 1 ohm. the blaster coil primary is rated at .7 ohms and measures .6 ohms. the resistance of the coil primary of the msd blaster coil and the added ballast resistor measures 1.6 ohms all measured on a digital meter. the recommended primary resistance for the coil on this vehicle is 1.34 to 1.55 ohms. i dont know what stress is being placed on the spark control computer when using the msd blaster coil with the stock ignition and no ballast resistor but the engine runs great under this configuration with very smooth acceleration a dead stop. the same is true when using the msd ignition box with the stock coil. the problem of a stumble on accelerating from a dead stop happens only when both are used together. with the addition of the ballast resistor the computer now sees what it was designed to see at the primary winding so there should be no problem of the kind you are warning me about having too low resistance at the primary. as to what is causing the stumble on accelerating from a dead stop using the msd ignition and coil and no ballast i am still in the dark. after all the engines performs great with just the coil and no ballast. jack 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. could it be because the high voltage is leaking out to ground somewhere on the way to the plugs i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
From : scott dorsey
hls nospam@nospam.nix wrote i am not really sure... i think you can look at the cable as a lumped-sum anyway. its pretty much just the resistance of the cable that will affect how much the coil will ring on the tail end of the pulse and i think that is the big deal. the inductance and the capacitance form the resonant circuit. the resistance is related to the q or quality factor. yes but the thing is that the coil inductance and the distributed inductance of the coil are so enormous that the cable doesnt contribute a whole lot. the cable impedance is pretty heavily swamped. someone mentioned spiral-wound cables for rf suppression... i have never used such a thing but they could have enough series inductance to change things. the most important part of that is that they will be a low pass filter. the resonant circuit is responsible for the ringing. i believe anyway it is but the coil resonance itself is so substantial that the cable shouldnt change it too much. it would be fun to measure it with a scope though and see how changing the cable length alters the waveform. it bet it doesnt do much but it would be fun to see. --scott -- cest un nagra. cest suisse et tres tres precis. .
From : ben91932
on dec 30 656=a0pm jack jack@thewildkingdom.com wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with 2 ppm hc is easy. retard the timing 2 degrees and it will drop right down... just to cover the bases... is the cat ok a temp gun should show a hotter outlet than inlet. does it run hot enough no 160 tstat absolutely no misfires a dollar bill held up to the exhaust should not vibrate. hth ben .
From : jack
jim wrote jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. normally when all is working as it should what limits voltage is the spark plug gap and the engine compression actually the absolute pressure inside the cylinder. a wider gap or more pressure will cause the voltage to climb higher before it will cross the gap. acceleration from a stop often will produce the greatest pressure inside the cylinder. could it be because the high voltage is leaking out to ground somewhere on the way to the plugs yes it could be that - if the voltage climbs too high too fast it finds another path instead of the spark plug gap. ultimately your ballast resister doesnt limit the voltage at the spark plug but it does slow down the rise in voltage which means that some other points in the secondary wont get quite as high. if stray arcing in the secondary is what is happening it would be likely that it would get progressively worse over time as the stray arcs develops a carbon trail that the current can follow more easily. the cause could also be in the primary there may be something that saturates in the primary or even something intended to limit voltage/current to protect against damage. -jim thanks jim for the feedback. i ran the engine at idle in the dark and could see no evidence of arcing. of course this is different from accelerating the engine under a load from idle. at any rate if the problem is caused by current leak do you think that changing the plug wires from 3000 ohms per foot to 500 ohms per foot would help it would only cost me about $50 or less to find out but i hate throwing money at a problem to see what sticks. jack i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
From : jack
hls wrote =20 normally when all is working as it should what limits voltage is the = spark plug gap and the engine compression actually the absolute pressure in= side the cylinder. a wider gap or more pressure will cause the voltage to = climb higher before it will cross the gap. acceleration from a stop often wi= ll produce the greatest pressure inside the cylinder. =20 this was especially true when the kettering system was used. when=20 capacitive discharged systems came along it pretty much stopped being true. thei= r rise times are so short and transformer action so definite that they us= ually=20 put up much more constant ignition performance. =20 i dont know what the multiple spark discharge systems do. are they cd= or something else hls the unit that i have is the msd 5900 blaster. it is not multiple spark but one strong spark through 20=b0 degrees of rotation and it is induction discharge not capacitive. but most if not all of msds other ignition units with the exception of the msd 5 are capacitive discharge. =20 some early studies showed that all things being equal a small single = spark ignited the fuel as well as anything else. some university studies in = england showed that high performance ignition systems which gave significant ga= ins were possible but they were not necessarily simple and cheap either. =20 it is my opinion and nothing more that there is little to be gained f= rom=20 systems like the msd for normal driving. for racing maybe....=20 i installed the msd components in the hope that they would help pass california smog requirements. i had to swap out the original feedback carb for a non-feedback version because the mixture control solenoid in the feedback carb is no longer being provided by anyone as a replacement part and owners of vehicles with this carbs are left to fend for themselves. i had the non-feedback carb installed the last time i had the truck smogged and it passed but only just. i was 2 ppm below the max for hcs. .
From : jim sjedgingn0sp
jack wrote i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. my guess is the cause is in the primary not the secondary. but if it was due to a leak in the secondary you would probably have to be looking at it in the dark while it was happening. changing the spark plug wire resistance shouldnt have any effect. current doesnt really flow thru the wires until the spark plug starts to arc. the tail end of the wave form will be affected but not the initial spike. getting rid of the resistance wont change the peak voltage in a measurable way. it is not clear how this is going to help with your emissions. if the mixture ia a bit rich all the spark in the world is going to get the extra fuel to burn. if it is a tad lean it might help but it doesnt sound like that is the case. -jim well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack .
From : hls
i am not really sure... i think you can look at the cable as a lumped-sum anyway. its pretty much just the resistance of the cable that will affect how much the coil will ring on the tail end of the pulse and i think that is the big deal. the inductance and the capacitance form the resonant circuit. the resistance is related to the q or quality factor. the resonant circuit is responsible for the ringing. i believe anyway .
From : jack
scott dorsey wrote jack jack@thewildkingdom.com wrote from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the ballast resistor does more than just change the voltage it can change the shape of the pulse through the coil as well. what role does the resistor play when voltage is cut off to the primary this is what causes the secondary to produce its voltage right the sudden collapse of the primary field does the inductance produced by the expanding field of the primary limit the rate of expansionof the field is this why there is not a high voltage produced in the secondary when voltage is applied to the primary could it be that the lower resistance of the msd coil primary over the stock coil .6 to .7 ohms compared to 1.3 to 1.5 ohms coupled with the greatly increased voltage to the primary from the msd ignition could cause the field in the primary to expand too quickly and cause a weak spark at the plug at the wrong time now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. no using a wire with a lower resistance will slightly increase the voltage to the plug. but honestly the difference is very small because the voltage is so high and current so low that it takes a lot of resistance to cause much drop. scott this was what i suspected. it seemed to me that the higher the voltage the less impact high resistance wires would have. my thought was that perhaps the higher resistance wires was causing current to leak out somewhere besides the plug gap. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. what you want is an ignition system analyzer that will let you look at the signal coming out of the coil on a crt. this will tell you what is really happening when you put the ballast resistor in. ask older shops around town if they still have an analyzer kicking around. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. the scope will tell you and without the scope you have no real chance of seeing what is happening. --scott thanks scott. i really appreciate your input. jack .
From : jack
donotspamme@my-deja.com wrote jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. im going to say msd designed the output section of their ignition system wrong and maybe when the resistance is low it goes into current-limiting mode to protect itself. another possibility is the high voltage protection for the output section typically some zener diodes and capacitor is interacting badly with the coil primary. msd recommends that these two units be used together on an ignition system such as the one in the 87 dodge dakota 3.9l. i am not saying that this means squat just that this is their recommendation. the msd ignition alone was causing the stock coil to get so hot that i could not keep my fingers on for more than a second after a good run which is why i got the coil that msd recommends. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. high voltage leakage shouldnt be a problem with modern 1980s and later distributor caps rotors and wires. on the other hand after i installed a cd ignition in my 1975 dodge dart 2 caps cracked in a few months. a slight modification to limit the primary voltage to under 400v stopped this. ah this interesting. how did you accomplish this if i might ask msd specs the 5900 as producing 420-450 volts to the primary. the stock 12+ wire to coil remains and msd adds another wire from the ignition unit to the + coil terminal and replaces the signal wire from the computer with another wire from the unit and the stock signal wire is connected to a third wire from the unit. a fourth wire goes to ground. here is a link to a pdf file of the wiring instructions for the unit http//www.msdignition.com/uploadedfiles/msdignitioncom/products/ignitions/5900instructions.pdf figure 2 is the one that applies. how might i lower the voltage as you have rather than installing a ballast resistor in the +12 volt wire to the coil. oh and thanks for sending the schematics for the different ignition systems. now that i have my system stabilized and running well i plan to check them out in detail. jack .
From : jack
jim wrote jack wrote i checked the engine at idle in a dark area at night and saw no evidence of arcing. could the high resistance wires be the cause if so what is the rationale i cant think of one. my guess is the cause is in the primary not the secondary. but if it was due to a leak in the secondary you would probably have to be looking at it in the dark while it was happening. changing the spark plug wire resistance shouldnt have any effect. current doesnt really flow thru the wires until the spark plug starts to arc. the tail end of the wave form will be affected but not the initial spike. getting rid of the resistance wont change the peak voltage in a measurable way. it is not clear how this is going to help with your emissions. if the mixture ia a bit rich all the spark in the world is going to get the extra fuel to burn. if it is a tad lean it might help but it doesnt sound like that is the case. -jim i will find out soon what the emissions are. i just got back from a freeway run and some stop and go driving and the only problem was a sag when i floored it at about 25 to 35 mph like the accelerator pump was out of adjustment or the power valve was not opening. i tweaked the pump linkage a bit but it wasnt out that much. i checked timing and it is at spec. checking the power valve will involve tearing into the carb which i will save for another day. it could be that the main jets are a tad too small but before i do anything else i will take it to a smog shop for a dry run to see what the emissions are. at least the ignition system seems to be performing okay and that was my main worry. .
From : jack
ben91932 wrote on dec 30 656 pm jack jack@thewildkingdom.com wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with 2 ppm hc is easy. retard the timing 2 degrees and it will drop right down... just to cover the bases... is the cat ok a temp gun should show a hotter outlet than inlet. does it run hot enough no 160 tstat absolutely no misfires a dollar bill held up to the exhaust should not vibrate. hth ben thanks ben ill definitely keep that in mind when the time comes. 5 btdc shouldnt look that much different from 7 btdc. there has been an annoying misfire at idle for quite some time although with the current ignition system that i described elsewhere on the thread the idle seems to have smoothed out considerably. but the smog test i have to take doesnt cover idle. it covers 15 and 25 mph on a dynamometer. sometime in the next week or two i am going to get a dry run at the smog shop to see what its reading. .
From : steve austin
scott dorsey wrote jack jack@thewildkingdom.com wrote from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the ballast resistor does more than just change the voltage it can change the shape of the pulse through the coil as well. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. no using a wire with a lower resistance will slightly increase the voltage to the plug. but honestly the difference is very small because the voltage is so high and current so low that it takes a lot of resistance to cause much drop. i dont have a clue as to why the engine stumbles with both the msd ignition and coil installed. from the symptoms it seems to me that it must be because of too much voltage at the coil tower but why that might be causing the problem is beyond me. what you want is an ignition system analyzer that will let you look at the signal coming out of the coil on a crt. this will tell you what is really happening when you put the ballast resistor in. ask older shops around town if they still have an analyzer kicking around. well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. the scope will tell you and without the scope you have no real chance of seeing what is happening. --scott the modern equipment would be the snap on modis or the snap on vantage pro. .
From : Annonymous
on jan 1 1233=a0am jack jack@thewildkingdom.com wrote ben91932 wrote on dec 30 656 pm jack jack@thewildkingdom.com wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having wi= th an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition wi= th 2 ppm hc is easy. retard the timing 2 degrees and it will drop right down... just to cover the bases... is the cat ok a temp gun should show a hotter outlet than inlet. does it run hot enough no 160 tstat absolutely no misfires a dollar bill held up to the exhaust should not vibrate. hth ben thanks ben ill definitely keep that in mind when the time comes. 5 btdc shouldnt look that much different from 7 btdc. there has been an annoying misfire at idle for quite some time although with the current ignition system that i described elsewhere on the thread the idle seems to have smoothed out considerably. but the smog test i have to take doesnt cover idle. it covers 15 and 25 mph on a dynamometer. sometime in the next week or two i am going to get a dry run at the smog shop to see what its reading.- hide quoted text - - show quoted text - jack from readin gall the above posts my guess is that the combination taht casues the stumble is for some reason casuing a weak spark. as one poster said it is hardest to develop spark during acceleration when compression is the highest so i guess there is some interaction in the electronics and the coil such that you have a poor spark at that time. somehow the 1 ohm ballast cures the interaction. i would leave the 1 ohm in the circuit and be happy but if you want to analyze this further i agree with another postr you will need a scope or ignition analyzer to look at the secondary waveforms and see just what is going on with and without the ballast. also as far as i know the purpose of resistance plug wires is to reduce radio interference. they dont really lower or raise the voltage of the spark at the plug. you are doing a great job at narrowing in on this.. but i think you need a scope to get to the next step. mark .
From : bob az
the vehicle manufacturer chrysler is the one that stuck me with an electronic feedback carburetor for which i cannot buy a replacement mixture control solenoid. do you really think they would grace me with advice and guidance get real. undoubly the manufacturer maximized the performance of your original ignition. bob =ef=bf=bdaz- jack all things considered i do believe the manufacturer is a good source. i have contacted chrysler myself and received good advice. and after a long evening conversation with a ford ignition systems engineer i am more aware of the choices that the manufactures make. remember i advised to contact the manufacturers performance folks. they have a periodic magazine that is available by subscription. i read all the issues at the dealer while getting my car and truck serviced. chrysler ford and gm do make decisions as to whether parts ar available and for how long. i did own a 87 chrysler 5th avenue for a number of years and i would expect to be able to locate whatever i would need for it. might take some time but if the demand is there the parts are usually available. in another instance just this past year i needed a fan blade for a 64 dodge pu and the chrysler dealer bent over backwards to locate one for me. took a few days but they called when they had the blade and there was no charge. bob az .
From : jack
makolber@yahoo.com wrote on jan 1 1233 am jack jack@thewildkingdom.com wrote ben91932 wrote on dec 30 656 pm jack jack@thewildkingdom.com wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with 2 ppm hc is easy. retard the timing 2 degrees and it will drop right down... just to cover the bases... is the cat ok a temp gun should show a hotter outlet than inlet. does it run hot enough no 160 tstat absolutely no misfires a dollar bill held up to the exhaust should not vibrate. hth ben thanks ben ill definitely keep that in mind when the time comes. 5 btdc shouldnt look that much different from 7 btdc. there has been an annoying misfire at idle for quite some time although with the current ignition system that i described elsewhere on the thread the idle seems to have smoothed out considerably. but the smog test i have to take doesnt cover idle. it covers 15 and 25 mph on a dynamometer. sometime in the next week or two i am going to get a dry run at the smog shop to see what its reading.- hide quoted text - - show quoted text - jack from readin gall the above posts my guess is that the combination taht casues the stumble is for some reason casuing a weak spark. as one poster said it is hardest to develop spark during acceleration when compression is the highest so i guess there is some interaction in the electronics and the coil such that you have a poor spark at that time. somehow the 1 ohm ballast cures the interaction. i would leave the 1 ohm in the circuit and be happy but if you want to analyze this further i agree with another postr you will need a scope or ignition analyzer to look at the secondary waveforms and see just what is going on with and without the ballast. also as far as i know the purpose of resistance plug wires is to reduce radio interference. they dont really lower or raise the voltage of the spark at the plug. you are doing a great job at narrowing in on this.. but i think you need a scope to get to the next step. mark thanks mark for the encouragement. i am *more* than happy with the ballast resistor. after i got things working right by putting one in the system i googled ballast at the msdigntion.com/forum site http//www.google.com/searchsourceid=chrome&ie=utf-8&q=ballast+sitemsdignition.com/forum and came up with a whole slew of posts regarding using a ballast resistor to compensate for the low primary resistance of the msd coil when used on a mechanical distributor ignition that uses a magnetic or hall effect pickup and electronics to fire the coil. the primary of the msd coil is .7 ohms and the replacement stock coil that i had been using was 1.7 ohms measured with a digital meter. msd mentions nothing in their instruction sheet for the coil or ignition about using a ballast resistor except when points are involved. neither is this info on any of the pages of their website except buried in the forums in answer to questions of people who are trying to install their units. so according to the advice of the msd techs i did the correct thing but it sure would have been a helluva lot less time and nerve consuming had they discussed the need for a ballast resistor in a non-points distributor in their instructions. in all the advice to people asking about this the techs would invariably state that *not* using a ballast resistor could result in the failure of the electronics that fires the coil in non-points systems. you would think that a company like msd would be more thorough in explaining in their installation instructions the correct way to wire up their units without causing damage to your vehicles electronics but here we are. im glad i held off buying low resistance wires. it didnt make sense to me that they would correct the problem i was having. .
From : bob az
well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack jack read dans reply more closely. i would suspect that too much primary current just supersaturates the coil and it doesnt discharge properly inhibiting the next charge/ discharge cycle. dan your post centered aound the ballast resistor selections. and dans post says it all. perhaps things would be improved by a rf coil or choke with a resistance of the same ohmage as the ballast resistor you have determined to work well. the secondary voltage is not really effected by the plug and or wire resistance. perhaps by their construction. the signal at the plugs is really a complex radio frequency waveform that without a good scope can not be interpreted. the usual monitor scope found in the garage is not up to this. and finally the manufacturer of your ignition should probably not be in businees at all. they know little if anything about ignition systems. you vehicle manufacturer should be relied on. contact their high performance folks for advice and guidance. undoubly the manufacturer maximized the performance of your original ignition. bob az .
From : jack
bob az wrote well thats it. at present i am more than happy with the ballast resistors. the truck runs great. just curious as hell as to what might be going on. jack jack read dans reply more closely. i would suspect that too much primary current just supersaturates the coil and it doesnt discharge properly inhibiting the next charge/ discharge cycle. dan your post centered aound the ballast resistor selections. and dans post says it all. perhaps things would be improved by a rf coil or choke with a resistance of the same ohmage as the ballast resistor you have determined to work well. the secondary voltage is not really effected by the plug and or wire resistance. perhaps by their construction. the signal at the plugs is really a complex radio frequency waveform that without a good scope can not be interpreted. the usual monitor scope found in the garage is not up to this. and finally the manufacturer of your ignition should probably not be in businees at all. they know little if anything about ignition systems. you vehicle manufacturer should be relied on. contact their high performance folks for advice and guidance. the vehicle manufacturer chrysler is the one that stuck me with an electronic feedback carburetor for which i cannot buy a replacement mixture control solenoid. do you really think they would grace me with advice and guidance get real. undoubly the manufacturer maximized the performance of your original ignition. bob az .
From : mike
donotspamme@my-deja.com wrote jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. im going to say msd designed the output section of their ignition system wrong and maybe when the resistance is low it goes into current-limiting mode to protect itself. another possibility is the high voltage protection for the output section typically some zener diodes and capacitor is interacting badly with the coil primary. msd recommends that these two units be used together on an ignition system such as the one in the 87 dodge dakota 3.9l. i am not saying that this means squat just that this is their recommendation. the msd ignition alone was causing the stock coil to get so hot that i could not keep my fingers on for more than a second after a good run which is why i got the coil that msd recommends. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. high voltage leakage shouldnt be a problem with modern 1980s and later distributor caps rotors and wires. on the other hand after i installed a cd ignition in my 1975 dodge dart 2 caps cracked in a few months. a slight modification to limit the primary voltage to under 400v stopped this. ah this interesting. how did you accomplish this if i might ask msd specs the 5900 as producing 420-450 volts to the primary. the stock 12+ wire to coil remains and msd adds another wire from the ignition unit to the + coil terminal and replaces the signal wire from the computer with another wire from the unit and the stock signal wire is connected to a third wire from the unit. a fourth wire goes to ground. here is a link to a pdf file of the wiring instructions for the unit http//www.msdignition.com/uploadedfiles/msdignitioncom/products/ignitions/5900instructions.pdf figure 2 is the one that applies. shouldnt you be using figure 4 for your truck unless you have switched to a points distributor have you tried wiring it using figure 4 to see if it would run any better .
From : jack
bob az wrote the vehicle manufacturer chrysler is the one that stuck me with an electronic feedback carburetor for which i cannot buy a replacement mixture control solenoid. do you really think they would grace me with advice and guidance get real. undoubly the manufacturer maximized the performance of your original ignition. bob =ef=bf=bdaz- =20 jack =20 all things considered i do believe the manufacturer is a good source. i have contacted chrysler myself and received good advice. and after a long evening conversation with a ford ignition systems engineer i am more aware of the choices that the manufactures make. =20 remember i advised to contact the manufacturers performance folks. they have a periodic magazine that is available by subscription. i read all the issues at the dealer while getting my car and truck serviced. =20 chrysler ford and gm do make decisions as to whether parts ar available and for how long. i did own a 87 chrysler 5th avenue for a number of years and i would expect to be able to locate whatever i would need for it. might take some time but if the demand is there the parts are usually available. =20 in another instance just this past year i needed a fan blade for a 64 dodge pu and the chrysler dealer bent over backwards to locate one for me. took a few days but they called when they had the blade and there was no charge. =20 bob az bob youll have to excuse me for being a jaded. i bought this truck new and have taken very good care of it. that fact that i cannot buy a $60 replacement part that is crucial to running the truck has caused me seemingly unending problems. how would one find these performance folks on the net .
From : bob az
bob youll have to excuse me for being a jaded. i bought this truck new and have taken very good care of it. that fact that i cannot buy a $60 replacement part that is crucial to running the truck has caused me seemingly unending problems. how would one find these performance folks on the net- hide quoted text - - show quoted text - if i remember correctly i called them from a number i got at the dealer who had their magazine in the waiting room. i would go to the dodge site to locate an internet address for the dodge performance people. or ask at the service counter. bob az .
From : napalmheart
bob youll have to excuse me for being a jaded. i bought this truck new and have taken very good care of it. that fact that i cannot buy a $60 replacement part that is crucial to running the truck has caused me seemingly unending problems. how would one find these performance folks on the net- hide quoted text - - show quoted text - if i remember correctly i called them from a number i got at the dealer who had their magazine in the waiting room. i would go to the dodge site to locate an internet address for the dodge performance people. or ask at the service counter. bob az you might also try these guys. http//www.manciniracing.com/ .
From : jack
mike wrote donotspamme@my-deja.com wrote jack wrote 1987 dodge dakota 3.9l carbed i recently posted on rec.autos.tech about the problems i was having with an msd 5900 blaster ignition and an msd 8202 baster 2 coil. it seems i could use one or the other with no problem either the msd ignition with the stock coil or the msd coil with the stock ignition but if i had both installed i would get a stumble on accelerating from a dead stop. from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the stock coil has about a 1.5 ohm primary and the msd coil has a .7 ohm or so primary. i dont know what impact this has on the situation but its info that i have and i figured i might as well throw it in if i am going to all the trouble of posting this and you are going to all the trouble of reading it. im going to say msd designed the output section of their ignition system wrong and maybe when the resistance is low it goes into current-limiting mode to protect itself. another possibility is the high voltage protection for the output section typically some zener diodes and capacitor is interacting badly with the coil primary. msd recommends that these two units be used together on an ignition system such as the one in the 87 dodge dakota 3.9l. i am not saying that this means squat just that this is their recommendation. the msd ignition alone was causing the stock coil to get so hot that i could not keep my fingers on for more than a second after a good run which is why i got the coil that msd recommends. now we get to meat of the my puzzlement. the ignition wires that i have on the engine measure about 3000 ohms per foot. for about $45 i can buy some msd street fire wires that are only 500 ohms per foot. i know a bit about electricity but not enough to know whether or not these wires would enable me to run the msd ignition and coil without the ballast resistor. after all the point of an msd ignition upgrade is to get longer stronger spark to the plug. low resistance actually doesnt help in most cases probably because it slows the rise time turn-on of the current and ive heard of many people running into trouble when they switched to low-resistance plug wires. high voltage leakage shouldnt be a problem with modern 1980s and later distributor caps rotors and wires. on the other hand after i installed a cd ignition in my 1975 dodge dart 2 caps cracked in a few months. a slight modification to limit the primary voltage to under 400v stopped this. ah this interesting. how did you accomplish this if i might ask msd specs the 5900 as producing 420-450 volts to the primary. the stock 12+ wire to coil remains and msd adds another wire from the ignition unit to the + coil terminal and replaces the signal wire from the computer with another wire from the unit and the stock signal wire is connected to a third wire from the unit. a fourth wire goes to ground. here is a link to a pdf file of the wiring instructions for the unit http//www.msdignition.com/uploadedfiles/msdignitioncom/products/ignitions/5900instructions.pdf figure 2 is the one that applies. shouldnt you be using figure 4 for your truck unless you have switched to a points distributor have you tried wiring it using figure 4 to see if it would run any better thats what i thought when i first got the unit over a year and half ago and thats the way that i first wired it up. didnt start that way. i got nothing but cranking when i turned the key to start. again msd is totally remiss in their instructions about wiring up a *hall effect* pickup as opposed to a *magnetic* pickup. one has to dig into their forums to discover that a hall effect pickup is wired the same as a points system and not as a magnetic pickup system. notice that a hall effect pickup is not mentioned in the wiring instructions. however preceding the figure 2 diagram is a key to the colored wires of the 5900 unit. notice that the white wire is for points or *electronic ignition trigger*. on my truck 87 dak with 3.9l engine the hall effect signal from the distributor is sent to the spark control computer where it is processed and amplified and then sent to the coil. this is the same signal that a points system sends directly to the coil and after much frustration and finally an email to msd i realized is the electronic ignition trigger referred to in the instructions. both are to be connected to the white wire. i can only assume from the wiring setup in figure 4 that the signal from the *magnetic pickup* is already processed with spark
From : steve
scott dorsey wrote jack jack@thewildkingdom.com wrote from this behavior i deduced that for some reason the problem was being caused by too much ignition voltage. to test out that theory i installed a 1 ohm ballast resistor in line with the +12 volts going to the coil. voila the problem vanished and i was back to strong smooth acceleration from a dead stop. so then i tried a 1/2 ohm ballast resistor and the stumble returned but not as bad so i went back to the 1 ohm resistor. the ballast resistor does more than just change the voltage it can change the shape of the pulse through the coil as well. and suppresses ringing in the circuit. and given the fact that the electronics that drive the coil are basically analog amplifiers it changes their output current profile directly too. .
From : steve
jack wrote bob youll have to excuse me for being a jaded. i bought this truck new and have taken very good care of it. that fact that i cannot buy a $60 replacement part that is crucial to running the truck has caused me seemingly unending problems. well they cant keep everyething in production forever. i rather doubt that i could go to a chrysler dealer and buy a carburetor for my 1949 plymouth club coupe either ;- everything becomes obsolete eventually and you have to come up with acceptable replacements. how would one find these performance folks on the net chryslers performance aftermarket segment mopar peformance can be found at http//www.mopar.com/performance/index.html but frankly theyre not nearly as helpful for the old-school carbureted guys as they used to be. theyre too busy selling crate versions of the new hemis for people to retrofit into their muscle cars not a bad idea but its gotten too dominant for my tastes. and on top of that youre looking for parts for an 80s 2-bbl v6 not a 1969 440 magnum. id take a look at places like manciniracing.com edelbrock.com summitracing.com jegs.com just off the top of my ol noggin ;- .
From : bill putney
steve wrote ...everything becomes obsolete eventually and you have to come up with acceptable replacements... reminds me about the old joke about the man talking about his axe yep - ive had this axe for years - best axe ive ever owned. all ive ever had to do to it was replace the handle twice and the head once. -- bill putney to reply by e-mail replace the last letter of the alphabet in my address with the letter x .