Tranny issue?

2000 XJ 4.0L/NP231/AW4 - 110k miles
2" lift, 30x9.5 BFG A/Ts, flowmaster 2.5" exhaust and 63mm TB. Otherwise stock.

Recently my Jeep has a strange issue with shifting. It seems more noticeable after swapping in a bored out throttle body. The issue probably happens about once every time I drive it. The tranny fluid is pink and filled to the correct level.

I will be driving the jeep at around 30 mph, and when going around a corner I will take my foot off the gas pedal. Once applying my foot to the gas pedal again, the RPMs rev up and it almost seems like the tranny slips before it shifts into the next gear. I don't think its slipping, but it almost seems like it goes into too low of a gear then switches to the next one in about a second. It doesn't happen all the time, and always seems to happen in the same spots where I drive. I'm wondering if this is a TPS issue? I adjusted the kickdown cable and that didn't change anything. It seems to run fine otherwise and I have a transmission cooler so I don't think it is heating up. Any advice is appreciated. :roll:

bump

when in doubt about aw4 shifting.... check the tps (also indicated by you mentioning you swaped throttle bodies). i cannot say for sure, but it doesnt seem like youve got a lot of other suggestions.

I doubt there is anything wrong with the AW4. My XJ does the same thing. At certain speed, load, road conditions and trottle input the AW4 does some gear hunting,...to me it is as if it is trying to descide wether it go to 2nd or 3rd gear thus increasing the RPM by about 200 RPM for 1 or 2 seconds before settling down. Usually it is the exhaust tone especially a loud exhaust that alerts me that the AW4 is not sure what gear to be in. Try to recreate the problem at different speeds and trottle input.

I've messed around with it and I'm starting to believe it is the TPS. Its exactly as you describe with the hunting around for a gear, and only happens at lower speeds (30ish mph) and in the same spots around town. I can try to recreate it but the issue only occurs once in awhile. My guess is that with the 63mm throttle body, the more sensitive throttle is messing with the TPS. I reset the computer when I installed it but I might just try my stock TB and see if it changes anything.

Would a new TPS make a difference? Is this a part I should buy at the dealer?

very interesting. Any updates?

Going to swap throttle bodies today after work, then see if anything changes. After that, might try a new TPS since mine is the original.

Transmissions, glad to hear you are not talking about women that are actually men, nasty.

1989TwoDoor said:

Transmissions, glad to hear you are not talking about women that are actually men, nasty.

Click to expand...

He was actually talking about the type of tranny that hang out behind an engine not those with 2 legs. I should know, I have seen my fair share at South Beach Miami FL.

I would not do anything to the XJ unless it slips excessively. A minor change in your driving style is all that is needed,....manually shift the gear if you think it will happen..... a little less or more of the go pedal.....

True slippage is usually not related to the throttle position sensor.

However, the TPS is so directly connected to shifting characteristics of the AW4 that you must completely rule it out before moving onto more complex possibilities.

So either test the TPS fully, or replace it. They aren't particularly expensive. Aftermarket seems to be okay for this sensor.