AW-4 shifting issues...

I've got a co-worker who just bought a 1990 XJ Laredo with the 4.0, AW-4, NP242, etc. It has 206,000 miles and seems to have been regularly maintained. It hasn't been modified in any way.

While driving it under normal conditions in 2wd, it will suddenly rev-up a couple grand and the transmission won't shift into overdrive. It seems like a severe slipping issue. She has had the related sensors replaced and/or cleaned, but it still does it. She has tried leaving it in 3rd and left the comfort/power button on and it still does it, but not quite as much as when in D.

The weird part is that it seems to do it much more frequently when turning to the right. She is going to replace the filter and fluid to see if that helps any.

Does anyone have any other suggestions as to what could be causing the problem or has anyone had a similar experience? Any help would be greatly appreciated!

:dunno:

Thanks, -Brian.

I'd suggest asking a mod to have this moved to the OEM Tech section. Can't be of much help otherwise, but it'll get you more traffic with knowledge.

With that said, have you checked the TPS?

~Scott

Alright. And yes, they tried the TPS. That was my first guess.

Unplug the TCU and drive it shifting manually.

No change, it is a mechanical/pressure issue.

Change, it is electrical.

That's a good idea, I'll have her try that. Thanks.

I wanted to post a followup to this: Did she see any change when driving with the TCU unplugged? My wife's '89 XJ has a similar issue I'm researching and came across this post. Please keep us informed!