Calling AW4 experts - need help troubleshooting

I am having a shifting issue with my 2000 XJ auto - 4.0, NP242, around 89000 miles on the clock.

Here is what it is doing -

During a lot of stop and go traffic (like rush hour), after coasting down or slowing down, when I then accelerate, the transmission will seem to slip, then drop into gear. You can see this on the tach, as the RPM will come up about 300-400 rpm and then drop back down. This is usually around 20-30 mph, and between 2nd and 3rd gear, so I don't think it's the torque converter locking up. Feels much more pronounced than that. Doesn't happen very often (less than once a day, sometimes 2 or 3 times a week.)

Here is what I have done so far -

Pulled the pan, changed the fluid & filter (fluid looked OK, only had about 20k miles on it) - there wasn't any significant buildup of clutch material (only a very slight grey film on the bottom of the pan), and only a light fuzz on the magnets. No trash in the strainer screen. I checked the soleniods, they were dead-on at 13 ohms. One odd thing was one of the crossover tubes between the valve body and the main trans body was loose, and had came partway out. I removed it, flaired the openings slightly, and pressed it back in, and it is now tight. I also checked the TV cable, and adjusted it per the factory manual (it was actually already properly adjusted, I just verified it)

The check engine light is not on either.

At this point, I am suspecting either the valve body is sticking, or a possible electronic control problem, but I am not sure, since there is no MIL lit. Any ideas would be great!

TPS? It seems to me that 80-90% of all AW4 shifting problems stem from the TPS.

Haven't checked it yet - was thinking about going ahead and replacing it. John at John's Transmissions in Bryan, TX (who has done work for me before on Toyota trannies that were pretty much bulletproof) seemed to think that it might be a pressure problem or a forward sprag going bad.

I doubt there is a mechanical problem, the AW4s usually go 2-300k miles without mechanical problems.

Your description sounds like when you're slowing down the computer is telling it to shift to first, then when you get back on the gas it revs up in first a bit before the computer realizes it should be in second.

For the $50 or so bucks, I'm going to try the TPS first. Besides, with 89k on the clock, it can't hurt, right?

MightyXJ said:

For the $50 or so bucks, I'm going to try the TPS first. Besides, with 89k on the clock, it can't hurt, right?

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I wouldn't consider 89k high at all. When I swapped my AW4 in I had no concerns at all about throwing one in with 130k.

But yeah, couldn't hurt, and if it doesn't fix it, just return the TPS and get your $50 back.

Found a OEM TPS here http://www.allchryslerparts.com/ for $25 plus shipping. blaise

Did you by chance get the part #? When I search for this part# - 4874371AC, it comes up $54.91 + shipping. This is the part number that the parts catalogue calls out for.

My buddy solved his AW4 hunting problem by adjusting his kick-down cable. It's the one that has the little half-moon shaped ratchet clip, look for this about 4" inboard from the throttle body. With the engine off, push the clip in with your left hand to release and with your right hand, feed the cable housing away from the throttle body until it stops. Now jump into the driver's seat and slowly press the skinny pedal (accelerator for the slow folk) all the way to the floor.

If you think you'll save some time by rotating the throttle lever by hand while under the hook and not by getting in and pressing the skinny pedal with your chubby foot, the kick-down cable will not be accurately adjusted.

Hope this helps.

That's pretty much what the trans shop told me ... in fact, John actually suggested that I adjust the cable a little different, so as to increase the line pressure.

My bad MightyXJ. That price was for my '90. I tried to edit my post, but it didn't work. blaise

blaisetd said:

My bad MightyXJ. That price was for my '90. I tried to edit my post, but it didn't work. blaise

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No problem - thanks for going thru the effort to find it!

Actually this sounds normal - like the t/c is unlocking while you accelerate, and locking up again once you're back up to speed. You can reproduce this by tapping the brake pedal with your left foot while maintaining steady throttle with the right. You should see the t/c unlock and the rpm jump a few hundred rpm.

Well, I would normally agree, except it is happening at about 15-20 miles per hour ... the torque converter doesn't lock on mine until about 45mph in OD ....

MightyXJ said:

Well, I would normally agree, except it is happening at about 15-20 miles per hour ... the torque converter doesn't lock on mine until about 45mph in OD ....

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the TCU will only lock the torque convertor in 3rd or 4th gears, so that makes sense.

BrettM said:

the TCU will only lock the torque convertor in 3rd or 4th gears, so that makes sense.

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This is true, assuming the shifter is in (D). Per the 2000 FSM, it will lock in second gear if the shifter is in (1-2), and third in (3). I swear my 89 locks up in second gear in the comfort mode, though. So it shouldn't be the torque converter engaging at that speed. In that case, I'm going to agree with Brett that the TPS should be checked out. If the computer isn't getting a good read on throttle input, it will shift strangely.