i have a 98 cherokee limited 4.o 230k miles
its been giving me trouble ideling after warm and terrible mpg and a real bad sputtering on the highway!
Just did a full tune up plugs wires oil change. still nothen.
took and cleaned the idle control valve and that helped in town but not mpg or sputtering...
replaced a broke O2 sensor fuse then cleaned the O2 sensor in town it seemed much better but then got on the highway and its sputtering as if its gasping for air and mpg is 10-12 used to be a low of 18- and high of 22
also replaced the oil pressure switch since that gauge was dancing and that helped that issue
for the life of me i cant find or figure out why the highway is so terrible on mpg and car doesn't excel or hold gas without sputtering terribly
This may be a silly question, but is your exhaust manifold cracked? Mine was and my mpgs dropped in half. Also, added air (oxygen) entering before the upstream O2S will trick the sensor into thinking your running lean, therefore, CPU will dump more gas into cylinders possibly causing slight wet fouling (slight skip) and P0171 (lean bank 1). Very interested in what you find, please keep us informed. Good luck!
The wires are all attached, also i did have to splice a year ago because of that reason!... will check manifold but unsure what exactly to do other than look at it i guess? Theres so much grease buildup so ill have to clean it first but i will update soon!
i didnt see any crack in the exhaust manifold, next i looked at fuel injectors... manually unplugged one at a time! One in particular after being unplugged didn't seem to foul the engine any more than when it was plugged in... so i ordered a set of bosh fuel injectors to arrive early next week and i'll update then!
Any suggestions or tips for changing out fuel injectors?!?!
gas mileage dropped suddenly to well below 12 oh highways when i was getting 18-20, idles still feel like engine will die and it has almost no acceleration unless its to the floor and even that my check engine light blinks when i do accelerate