High revving 4.0

[JIMBOJAMES]

OK I have a 96 with a AW4 tranny. Well gooing down the road the Jeep will be cruising then out of no where start to rev up then go back down. It does it mostly at cruise. I just pulled my tranny out and replaced th front seal in it.

 

[jeepdude10000]

im going to say something with the cruise.

 

[Yucca-Man]

Sounds like Torque Converter unlock - how much does it rev up?

Got stock tires and gears, or is it running larger-than-normal on stock gears?

Got Dexron-III??

 

[JIMBOJAMES]

I didnt mean cruise control I mean cruising at a good a nice speed. Anyway I am running 33s with stock gearing. I am running Dexron III could I be running a better fluid. Example I a driving down the road at 55 at 2000 RPM then it goes to 3500 when I did not change the pressure on the pedal.

 

[BeJay1981]

Check to make sure everything thing is hooked up, maybe you pinched a vac line or forgot a plug somewhere. It's something simple....guarenteed.

 

[JIMBOJAMES]

Check to make sure everything thing is hooked up, maybe you pinched a vac line or forgot a plug somewhere. It's something simple....guarenteed.

It would be great if your right.

 

[Yucca-Man]

Anyway I am running 33s with stock gearing.

Regear.


The tranny is unlocking and downshifting...and is working harder than normal because it's turning the 33s with stock gears.

 

[JIMBOJAMES]

I do agree I need to regear but I have been running the 33's for 2 years and have not had any issues until now.

 

[jeepdude10000]

It might be TPS. It sends info to computer whitch sends info to tranny puter.

 

[UNCC_99XJ]

It might be TPS. It sends info to computer whitch sends info to tranny puter.

That's what I was gonna say. I ran into a similar problem back in April. I was driving down the highway (i dont have cruise control), running about 70-75 with the a/c on. Out of nowhere it started randomly shifting. It would go to 3rd, hold for a couple of seconds, then back to 4th. I kept driving down the road to see if maybe it would stop and it didn't. I pulled over and let it sit a couple of hours on the side of the highway and cool off. Went back to get it and it hasn't done it since. CEL was already on for the o2 sensor (i was actually on my way back from getting that checked out at autozone when this happened) and it threw a code for the TPS, but i can't remember exactly what code for the tps is threw.

So you might look into that. What year is your XJ?

 

[hubbler]

I had the same problem with my 89 XJ, I would be cruisin down the road and the idleing would jump up and down. I found it was the Idler Air Control motor. I replaced it and had no troubles.