AW4 question

I have a 95 XJ with the AW4 transmission and I have a question about it. I understand that its a very tough transmission and rarely needs replacing, but mine is not shifting as smoothly as it used to. It shifts great in every gear except when shifting into second its kinda jerky and a slower shift than the other gears. It only does it when I drive with the accelerator about half way down, other than that it shifts normally into second. Also, this could be completely normal, but if i give it a constant throttle it shifts at 3000 rpms in first and close to 3500 in second. It seems to me like something is out of adjustment, but I don't know much about automatic transmissions. Are there any cables or anthing that can be adjutsted on it? I've also heard that there are a few sensors that can fail on the transmission that can cause poor shifting. Is this true?

Please excuse my ignorance on automatic transmissions.

Oh yeah, it only has 88K on it and I recently dropped the pan and changed the filter and the fluid in the pan (only 4 quarts). As far as I know its never had a transmission flush.

Shifting on the AW4 is electronically controlled. The TCU (transmission control unit) controls the operation of the solenoid valves. The TCU depends on readings from sensors to do its work. When the Throttle Position Sensor (TPS) gets out of range, the result is wonky shifting and sometimes high idle. You have an advantage in having a 1991 or later XJ- you can just stick in a new TPS, no adjusting to specifications involved like on the earlier ones.
I prefer a complete fluid change on the AW4. This can be done by one of those machines at the oil-change-place that sucks out all the old an replaces it with new through the tranny cooler lines, or do-it-yourself by disconnecting a cooler line and taking out 2 litres/quarts at a time, adding two, then taking out two more, etc until done. I use a 2 litre pop bottle: fill it with fluid out, then add 2 back into the filler tube. A real tranny cooler ( the kind out in front of the radiator, not the little deal in the rad) is great for tranny life too, since heat kills them. 4XBob

Thanks, it looks like an easy job. Is that the same sensor thats on the side of the throttle body, or is there a different one?

BTW, I'm planning on getting the transmission flushed ASAP.

Atl XJ said:

Thanks, it looks like an easy job. Is that the same sensor thats on the side of the throttle body, or is there a different one?

BTW, I'm planning on getting the transmission flushed ASAP.

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don't flush your tranny. just change the fluid. and check the tps on the throttle body.

Why would you recommend against having it flushed? I only have 88K on my Jeep. :huh:

Atl XJ said:

Why would you recommend against having it flushed? I only have 88K on my Jeep. :huh:

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just a personal opinion..

feel free to ignore it.

I understand that, but you must have some motivation behind this thinking.

As I was told if you flush your tranny every 30k then it is good to be religious about it and do every 30k.. However if you don't flush it religiously then it was recomended to me just to change the fluid.. Reason for this is after running the tranny for awile without regular maintenance the tranny develops nicks and cracks inside and by not flushing it, it leaves a buildup (or residue)that fills the nicks and cracks from potential leaks... atleast that's how it was explained to me.

I think he means dont power flush it. The reason for that is... That any loose metal shavings or dirt that is in there may really mess things up if it starts moving around. Power flush = bad news. Same with the radiator.

Tombs said:

I think he means dont power flush it. The reason for that is... That any loose metal shavings or dirt that is in there may really mess things up if it starts moving around. Power flush = bad news. Same with the radiator.

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Bingo. ..

just think of all that crap sitting in your TC... that is being flushed thru all the little galleys and such in your tranny... ouch.

I lost a aw4 this way once... never again will I flush a tranny.

The reason I want to have it flushed is because I used to have a pretty good leak out if the transmission pan and before I fixed it I added a couple of different brands of Dextron III to it when it was low. It shifted great when I got it and it still shifts okay, but not as smoothly as it used to since I added the fluid to it. I want to get all the old stuff out and make it uniform.

BTW, when I dropped the pan, the old fluid looked good and I found nothing bad at all inside there. I don't know much about automatic transmissions, but everything looked brand new in there. I didn't even need to change the filter really, it wasn't even dirty. I went ahead and changed it though for good measure.