AW4 question

The AW4 in my 95 XJ with 89K on it shifts great in all gears (very smoothly) except second. It shifts rough in to second gear, not horribly, but a lot rougher than I think it should. It only shifts rough during normal driving, if I floor it it shifts like it should. Also, it seems to shift pretty smoothly at first, but after its good and warmed up it starts shifting poorly. It only shifts poorly during upshifts, it downshifts fine. I changed the fluid and filter, not too long ago and I can't tell any difference. I also tried indexing the kickdown cable and it didn't seem to make much difference in second gear. Although, the other gears do seem a little smoother. I really hope I don't need a new transmission, I really can't afford one right now. Please tell me there is an adjustment or a sensor, or something like that, that can be performed to fix this.
Thanks :greensmok

The Throttle Position Sensor sends a signal to the TCU that is used in timing shifts. If the TPS signal is out of spec, then the AW4 automatic transmission gets the willies, and shifts badly or at the wrong times or both. It's a great transmission, given an occasional fluid change. The problem is usually in the sensors/electronics- don't let a shop tell you you need a rebuild if there's no big chunks in the pan! 4xBob

Thanks for the quick response. I was actually pleasantly surprised when I dropped the pan. Everything looked brand new and I only found very very fine metal shavings on the two magnets, everything looked good inside from what I could tell. I know really know jack about the internals of automatic transmissions though.

What is the correct proceedure for indexing the cable? I think I did it correctly but I want to make sure. I pressed the button on the cable, pushed the part where the cable comes out in as far as I could, and then while the button was pushed I gave it WOT. Are you supposed to release the button after you hit WOT, or leave it pressed until you release the throttle. Also, when adjusting the cable I pushed the part where the cable comes out all the way in, but it wanted to slide down some on its own before the throttle adjusted it. I had to hold it in with my finged for a second until the throttle adjusted it. Is that the correct way to do it? I'm not very good at explaining stuff like that. Does that make any sense?

Are there any other sensors that could be the culprit?
Thanks

I second 4xBob's suggestion of the TPS being bad. Since it only does this at part throttle, it's almost a lock that the TPS is worn. They tend to wear at the lower end of their range, because that's where most of the throttle movement is. It's easy to test with a multimeter.

Your cable indexing procedure sounds correct to me.

The TPS is on the throttle body right?
Thanks

The only thing that I don't understand is that if it were the throttle body, which it very well could be, then why is it only shifting poorly in second gear? :dunno:

I replaced the TPS yesterday and it is definitely shifting better. It used to stay in second gear too a little too long and its not dong that anymore and its smoother. Its still not as smooth as the other gears though. IDK why? Its good enough that I can live with it though if need be.

I have almost the exact same problem. All gear actually shift OK, but they are usually at too high of RPMs than they should be. 2nd gear is the worst at holding gear for a long time

what are the correct TPS voltages I should be getting? and off what wires

According to your profile you have a ZJ which uses a different transmission

So has anyone correlated the transmisison shift performance against the TPS settings? I.E. how does it shift using the 88% setting vs 90%?

Here's the TPS values for my 89, I assume the later models would be similiar:

Pin A = (reference voltage), approx 5v
Pin B = (signal voltage), 4.2v@closed throttle, .3v@fully opened throttle
Pin C = Not used
Pin D = (gound), less than .1v

The two things to check for are: (1) a smooth voltage transition on pin B from closed throttle to fully open. If it's erratic, then the TPS is worn and should be replaced. Then (2) check for a good ground on pin D. The specs say less than .1v, but I like to see 0 volts/0 ohms here. If you have a meter movement on this pin, splice an extra wire to pin D and run it to a bolt on the engine. This will give a better ground than the stock wiring.

All readings are taken with the key on, engine off. Check pin D first, because if the ground is bad, the other pin readings will be unreliable.
Hope this helps.
Don

Atl XJ said:

According to your profile you have a ZJ which uses a different transmission

Click to expand...

profile fixed, I got a different jeep
I have a 98XJ 4.0L

the aw4 is a very stout tranny. Iv had chunk of things in the pan and it still runs perfect lol.