Decreased fuel mileage question

From : leon taylor

Q: i have a 97 dodge dakota that the fuel mileage has went to half of what i have gotten in the past i have run a code test and nothing has shown up faulty. im getting black smoke from the tail pipes which indicates unburnt fuel . i have replaced the plugs and wires and the air filter is clean and no obstructions in the air intake hose but the problem still continues . my normal fuel mileage in the past has been 17-19 mpg hwy but now it is 10 mpg . my question is there a sensor problem that would not show up on the code test the engine is a 3.9 and auto trans . any help on this matter i would greatly appreciate. .

Replies:

From : Annonymous

on jul 10 300 pm mike nos...@nospam.com wrote i have a 97 dodge dakota that the fuel mileage has went to half of what i have gotten in the past i have run a code test and nothing has shown up faulty. im getting black smoke from the tail pipes which indicates unburnt fuel . i have replaced the plugs and wires and the air filter is clean and no obstructions in the air intake hose but the problem still continues . my normal fuel mileage in the past has been 17-19 mpg hwy but now it is 10 mpg . my question is there a sensor problem that would not show up on the code test the engine is a 3.9 and auto trans . any help on this matter i would greatly appreciate. check the operation of the front oxygen sensor with a scan tool. a failing o2 sensor can cause both the problems you decribe. also make sure with the use of a scantool that the map sensor is working correctly as well as the the coolant temp sensor .

From : Annonymous

on thu 10 jul 2008 121759 -0500 leontaylor@webtv.net leon taylor wrote i have a 97 dodge dakota that the fuel mileage has went to half of what i have gotten in the past i have run a code test and nothing has shown up faulty. im getting black smoke from the tail pipes which indicates unburnt fuel . i have replaced the plugs and wires and the air filter is clean and no obstructions in the air intake hose but the problem still continues . my normal fuel mileage in the past has been 17-19 mpg hwy but now it is 10 mpg . my question is there a sensor problem that would not show up on the code test the engine is a 3.9 and auto trans . any help on this matter i would greatly appreciate. i had a similar problem a few years ago on a different model. all at once black smoke and the mileage tanked. took it to a dealer and they replaced the oxygen sensor and changed the oil on the chance that all that extra fuel had diluted it. new oxygen sensor smoke gone mileage back up. i didnt check for any codes nor did i get a check engine light just a black smoke cloud. jerry o. .

From : mike

i have a 97 dodge dakota that the fuel mileage has went to half of what i have gotten in the past i have run a code test and nothing has shown up faulty. im getting black smoke from the tail pipes which indicates unburnt fuel . i have replaced the plugs and wires and the air filter is clean and no obstructions in the air intake hose but the problem still continues . my normal fuel mileage in the past has been 17-19 mpg hwy but now it is 10 mpg . my question is there a sensor problem that would not show up on the code test the engine is a 3.9 and auto trans . any help on this matter i would greatly appreciate. check the operation of the front oxygen sensor with a scan tool. a failing o2 sensor can cause both the problems you decribe. .