Weird Trans Issue and then some

Ok, first the tranny...for the past week or so when I have the cruise set around 60 (most common speed for this to happen, but not the only) the trans starts to jump back and forth between 3rd and overdrive. This is a 2000 cherokee with the AW-4 that has over 200K not-so-nice miles. Do you think this is electrical or the tranny is just done for? The other thing it does thats weird is when Im coming up to a red light, the rest of my momentum seems to catch up and hit me 2 seconds after I make a complete stop. I have many mechanic friends and they all think Im crazy for that one, but it definitely happens all the time. And heres the last one and maybe the weirdest....every single time I accelerate from a stop, the truck "wobbles" for lack of a better word just for a second or two. Maybe even call it a wiggle, but you can feel it move quickly from side to side almost like a dog wagging its tail. Any help would be greatly appreciated because I always swore Id own this truck forever, but now its really testing my patience. Thanks!

The tranny computer determines the shifting based on speed and throttle input. The TPS sensor on the throttle body can and does wear out and cause erratic shifting. I would look at that first for the odd shifting. It can be tested with a decent meter (preferably analog) or by the dealer using their computer. I believe cost is $30-$40 at the local auto store and pretty simple to replace.

The "momentum" and wobble are probably loose or sloppy suspension parts. Possibly a worn out track bar or bushing in the control arms.

Welcome to , btw.

All of the suspension is new...every bushing is urethane, all new shocks and springs. Even the tranny mount is new from mopar. I have a lot of time and money into maintenance, so it should all be just fine.

Are you talking about a clunk that happens after you stop? That might be a need to grease the rear driveshaft splines where it enters the xfer case.

Check the fluid level and condition, for starters!

I flushed the AW-4 in my 88 XJ and overfilled it by about a half quart, and every time I let off the gas at highway speeds it would kick down from OD to 3rd gear. Then I drained some out and was about a half quart low and it hunted like you describe. Got the fluid level right and it shifts fine now.

Yep, its a clunk after I stop, but its so bad it feels like I just got rear ended! As for the trans fluid level, Im pretty sure its dead on, but I can check again. I service the trans every 3rd oil change (9K) so Ive got it down pretty good after this many miles...never hurts to do the free things first though, right?

I'd try greasing the driveshaft splines as it's a pretty simple and no-cost thing to do. What happens it that is gets bound up under the torque and can't slide liek its supposed to. Once you stop and the pressue is off, it unbinds and lets loose with a clunk. You'll need a 5/16 wrench to undo the ujoint straps at the rear diff. You might need to pry the shaft forward with a screwdriver to get the ujoint to pop off, then slide the shaft out of the xfer case. Smear some bearing grease in the splined section and reassemble.

I recall another thread about something having some odd clunk after they stopped. So bad that they said they got out thinking the person behind them rearended them.

Ok, got a scanner today and confirmed that the TPS has something goin on because its not reading correctly, but it didnt throw the check engine light for whatever reason. Put in 4 new Bosch 02 sensors just for preventative maintenance, and of course now I have a check engine light! I ordered 4 Denso sensors in hopes this corrects the problem. Im gonna put it on the lift tomorrow and grease the splines and put in all 6 new u-joints. The one thing that Im still totally puzzled by is the trucks "wagging" upon acceleration...every time like clockwork no matter how hard or light I accelerate. WTF is it??? Also, off topic, since I thought the tranny might be bad, I was looking into swapping a 6-speed from an 06 rubicon into my XJ. Anyone know anything or anyone thats done this? How involved is it and would it even make sense? I can get the trans itself for $750. Whats everyone think?

It's pointless to replace the downstream sensors as they don't affect the engine at all. They are simply there to ensure the cat(s) are working properly. They only needed replaced if the computer says they are bad. When you said all the suspension stuff was new, did that include the rear?

Put in the new TPS today and the trans problem vanished...yes!!! And that does include the rear. If Im gonna do something, its gonna be done right. So, anyone know about that 6-speed swap????

how bout a bent rim or broken cord in one of the tires causing the wiggle

Does it do the clunk if you pop it into neutral before you stop? If not, that points to the driveshaft slipjoint at the xfer case binding. Off the top of my head, other things to look at would be rear leaf spring u-bolts, rear brakes, alignment (including thrust angle).

Definitely not the bent rim because its only from a stop for about 2 seconds and then its done. As far as if it does it in neutral or not, I dont remember. Its been doing this for at least 30K now, so Im sure I checked that at some point....Im gonna say it does it regardless. Heres a perfect example: Im on my way to work today and following a school bus....damn they stop fast for bein so heavy!....So Im going like 50-55 and have to stop like its a badly timed red light. I come to a full stop and then the ass end falls a little and it makes a clunk followed by a quick forward movement (almost as if the car behind me tapped me really lightly). The truck also always feels like its stopping harder than it is. If Im doing say 60-65 and get a poorly timed red light, it feels similar to a panic stop even though if I was in any other vehicle, it wouldnt. Yes, all of the brakes are new (rotors, pads, drums, shoes). Now, I used to have cross drilled rotors and ebc green stuff pads but I had to scrap them and go back to stock because they barely worked!

I read through... Did you mention that you did grease that rear slip yoke?

My 01 was clunking, so bad that it would shake change in the cup holders and it felt like I was getting hit. And if I would stop very very VERY slow and easy, it would clunk on accel.

Someone mentioned to grease the slip yoke...and I did a poor job of it. Recently, I re-did it. Really cleaned the splines, and loaded it with some good marine grease. Clunk is gone. Couldnt believe it. I really thought the trans was messed up. It seemed heat related, and way too violent to be the slip yoke. Apparently it happens in other vehicles..not just XJs...

J.

Cant say Ive greased anything yet, but that looks to be my next step because last night I was driving in the rain and noticed it wasnt doing it. That leads me to believe that the water gives it just enough lubrication to keep it from clunking....thats gonna next weekends project....Im just finishing the restoration on my 91 BMW and Im so so close to finished. But who knows about my wobble problem??? Think maybe the unibody is cracked???