1990 Dakota - emissions problems

From : alex mcclure

Q: hi i purchased a 1990 dakota convertible with a 3.9 litre throttle body injected engine and 5 speed transmission. it has failed a mandatory emissions test. the engine has 135000 miles on it. i am looking for advice on whether i need to rebuild the engine or not. at idle speed the truck passed the emissions test. however at 40 kph the hcs and nox were 2x higher than allowed while the co was well within limits. the mechanic showed me that the intake manifold passageway for the exhaust gas recirculation was plugged solid explains the high nox. he says that if i unplug this and put a new catalytic converter on that the truck should pass as it does not smoke out the tailpipe bad. my concern is that something is plugging the egr passage and will do it again quickly and poison the cat. converter too and in 2 years i will fail the emissions test again. i should mention that the valve covers are leaking badly. someone said to me that the valve guides may be the cause of the plugging of the egr passage. he said to do a compression test and if that is ok then do the valve guides and i should be ok. any thoughts would be appreciated. thanks alex by the way can i damage the electronic engine management unit by cranking the engine with the coil wire grounded out or what is the correct procedure when doing the compression test with a fuel injected engine .

Replies:

From : redneck tookover hell

someone said to me that the valve guides may be the cause of the plugging of the egr passage. he said to do a compression test and if that is ok then do the valve guides and i should be ok. any thoughts would be appreciated. go find yourself a real mechanic and have it fixed. most states have a maximum amount that you have to spend to fix a problem beyond that you will get a exemption for the smog test if you work on it yourself there is no maximum politics the gentle art of getting votes from the poor and campaign funds from the rich. .

From : oldtimer

on sat 12 jun 2004 105215 -0400 alex mcclure mercman55@cogeco.ca wrote hi i purchased a 1990 dakota convertible with a 3.9 litre throttle body injected engine and 5 speed transmission. it has failed a mandatory emissions test. the engine has 135000 miles on it. i am looking for advice on whether i need to rebuild the engine or not. at idle speed the truck passed the emissions test. however at 40 kph the hcs and nox were 2x higher than allowed while the co was well within limits. the mechanic showed me that the intake manifold passageway for the exhaust gas recirculation was plugged solid explains the high nox. he says that if i unplug this and put a new catalytic converter on that the truck should pass as it does not smoke out the tailpipe bad. my concern is that something is plugging the egr passage and will do it again quickly and poison the cat. converter too and in 2 years i will fail the emissions test again. i should mention that the valve covers are leaking badly. someone said to me that the valve guides may be the cause of the plugging of the egr passage. he said to do a compression test and if that is ok then do the valve guides and i should be ok. any thoughts would be appreciated. thanks alex it is not uncommon for one to have to clean out the egr valve every few years. it is not a difficult task. oldtimer .