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wj acceleration problems

10K views 15 replies 5 participants last post by  StoneCold 
#1 ·
02 WJ 4.7L with 90k miles engine problems or transmission problems… starts fine , good low end power but as you accelerate power dies off - dash lights blink trans light blinks “trans over heat” light comes on…no codes through.. I installed new plugs and air filter no change. condition does not seam to happen all the time. Also just did trans fluid and filters. Still does not want to power up any suggestion appreciated
 
#3 ·
Did you have those problems before changing plugs and fluids? Does it feel like the tranny/torque converter can not transfer the torque, or does it feel like the engine doesn't have enough power? I had some similar problem on my WJ. It was driving normally, but when accelerating it was lacking power. After changing the fuel filter/pressure regulator my problem was solved. Strange though that you also have the TRANS OVERHEAT light on. Is this light on all the time?
 
#5 · (Edited)
Is the tranny not changing gears? You probably have to go to some place where they can read the tranny faults. It can be an input/output sensor problem or some other senor in the tranny.
 
#6 ·
Trans changes gears fine.. just came back fron auto store and if i accerelate real easy it runs fine, as soon as i ask it to get up an go it stumbles if i keep accerelating it would probley stall when i baby it it will act normal and i can get it up to 60mph I am checking fuel rail pressure next thanks for the help
 
#9 · (Edited)
2002 jeep Grand Cherokee, Limited Silver with Black leather oil changed every 3000, K wife’s car babied been on the beach a couple of times but 99 percent a commuter car to and from work a (5 mile commute)

Started out the coldest day of the year 5 degrees. jeep gave wife problems did not want to get her to work. had code 0203 number 3 cylinder injector failure. I took # 3 injector out and switched it with number 4 injector no problem - no code but jeep still does not want to run pass ½ throttle if you baby it will run as soon as you push it quits.

Day two Replaced spark plugs with Mopar copper core # Mopar® P/N SPRC12MCC4
No change still quits above 50% throttle position
Pass ½ throttle if you baby it will run as soon as you push it quits


Day three had Trans code over heat so I changed the Trans fluid with ATF+4 fluid and both filters took for test run code 0300 “all cylinder misfire “
No change still quits above 50% throttle position
Pass ½ throttle if you baby it will run as soon as you push it quits


Day four replaced throttle body position sensor no change to performance
Still quits above 50% throttle position “all cylinder misfire”
Pass ½ throttle if you baby it will run as soon as you push it quits

Day four replaced manifold air sensor
No change to performance
Still quits above 50% throttle position “all cylinder misfire”
Pass ½ throttle if you baby it will run as soon as you push it quits. If you turn off key rough idle goes away but as soon as you push it pass 50% accelerator miss returns it will run a low speed all day long but as soon as you ask it to perform it gets all choked up a quits

Does mopar have a shrink I can sent this unit too because I am at my wits end
 
#11 ·
Thanks I did check fuel pressure at rail and it was 50 psig and held for quite a while so I don't think that is the problem…. I also do not think it is the trans because the miss accrues in neutral when the accelerator is pushed pass 3000rpm runs fine up to 3000rpm than stumbles if I shut it off and restart the miss is gone until I accelerate past 3000k.
 
#12 ·
I am down to three item’s either the crank position sensor CPS or the engine control module ECM unit is malfunctioning or possibly the catalytic convertor is somehow restricted. The CPS I have purchased from Mopar but I can not see it and it appears like a difficult job… has anyone had experience doing this replacement? (Most problems with the CPS seam to be they fail when the car heats up an restores after cool down) my problem is fairly consistent.

All help is appreciated thanks
 
#13 ·
It could be the CAT going bad, They usually really rear their ugly head the harder you press the gas pedal. Usually act fine when driven easily but I have seen them act other ways too. You ned to check fuel pressure under load when the problem is happening. Sitting in the driveway with good fuel pressure mean nothing except the fuel pressure is working. It may not supply the fuel pressure needed at speed and load. But that would not cause your tranny to overheat.

When a crank sensor usually goes the car typically will not run at all.
Same can go for the CAM sensor, they also can trigger a code from one another. Sometimes they share thye smae OBD2 code for CAM and Crank sensor.

Is the 0300 code the only one you have seen?
Are your cooling fans working properly?
 
#14 ·
The CPS should throw a code, I forget what one exactly from memory, P0320 I think. Granted it may not always throw a code. Mine went last year and the engine would just stop dead. Like a hard jolt. It would sometimes to do while cruising along, then bang! But the engine would keep on running, check light would come on. Only twice did it actually stall completely and both at very low speeds. It's located on the transmission and is a bit of pig to get to and whatever you do, don't drop the bolt!
 
#15 ·
Had three catalytic converters installed and the jeep is back running like it should. It did not like the restriction in the exhaust system, probably due to the plugs not being changed per the maintance schedule and unburned fuel contaminating the cats.. Learn from my lesson and don’t let this happen to you….. Change plugs every 30k and save the $1,000. I spent on new cats. Thanks for all your help
 
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