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gearhead

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Discussion starter · #1 ·
Has anyone else had this problem?

'94 ZJ (131k miles - 4.0L/42RE/249)...It sometimes does this...When I first shift into gear (still stopped with foot on the brake), there is a bad vibration and it feels like something is trying to stop the engine. The engine speed comes down and sometimes it even stalls. It seems to stall more readily if I back up quickly, come to a stop, and shift to D. Once I'm rolling, the vibration goes away and engine speed seems normal until I come to a stop at a light or whatever and then I get the vibration again. If I stop quickly, the vibration is worse. However, these symptoms will come and go.

I had a local tranny shop check it over and they couldn't figure it out. They said the tranny is a.o.k and referred me to another shop. I also talked to a fellow gearhead who helped develop the O/D unit for this transmission for NVG who is also puzzled.

It seems to me like it could be the torque converter lock up clutch trying to lock up when its not supposed to - ya know, like letting out the clutch on a manual tranny when your stopped with your foot on the brake. However, while I'm at highway speeds in O/D, I can see from the tach that the torque converter clutch is unlocking and locking, normally I think.

Has anyone heard of a problem with the torque converter clutch at high miles?

Any other guesses?
 
I have a 93 4.0 with the 42RE, 249 and 130k and mine does the same thing. It won't stall if I give it a little gas while my foot is on the brake. Just a little to bring the rpm up to about 8-900. And, yeah its defenitly worse with a quick stop or a R to D engage.
I wonder if bad engine/transmission mounts could cause this. Just a thought.

P.S. I'm from Jamesville just south Syracuse. What transmission shop did you go to?
 
Discussion starter · #4 ·
Tranny shop was Terry's Transmission on E. Taft Road.

I have emailed this question to an engineer at NVG who used to work at Jeep/Truck Engineering on the ZJ 4WD systems. He hasn't responded yet. If I find out, I'll pass it on.
 
rough idle...

If anyone gets info on this, please let me know as well. My friend and I both have 1998 models with the same problem... thanks.
 
in response to engine mounts, i doubt it's the problem. i took my 94zj (approx 90000miles at the time) in for another unrelated problem, and the mech found my engine mounts to be in HORRIBLE shape. like they were each cracked and dang near falling apart. once they were replaced and i took a look at the old ones, i could see what he was talking about. each one was cracked into at least 3-4 pieces and crumbling.

but for them being as bad as they were i never noticed a vibration like you're describing, not even close to a vibration. note that my tranny mount(s?) he said were still looking like new so i don't know about that part. .........good luck!
 
I have the same problem when I'm in reverse. The only way to keep it from stalling is to give it gas when it starts vibrating while still pressing on the brakes.
One thing I have notice is and havent fixed is that the tranny mount is shot. Maybe that has something to do with it.
 
sounds like there is a convertor issue. could be a sensor or the actual convertor.

mine has similar issues when the fluid gets low from my front seal leak. this is the only trans i've ever had that acted this way from being 1 qt low.

good luck.

robert
 
I am begining to have the same near stalling issues. Although it has never completely stalled but has come close. It is a AW4 tranny with an I6. Although my issues seem to be intermittent. It doesn't happen after a cold start, only begins after the engine has warmed up and especially after I run a short while turn of the engine and then start it again, like after running an errand.

It being intermittent has lead me to beleive that it is an electrical problem. Most intermittent problems are electrical, so I am kind of thinking that it could be the fuel pump or some other electrical/spark related problem.

Does your guys engines do this while in park and tapping on the fuel filter or gas tank? I haven't checked mine but I think this may be the case. I have changed the fuel filter before but I am suspecting it may be bad.

If this is not the case and is the tranny, you think having the fluid flushed help? Cheaper than a tranny rebuild.

Chad
 
My '93 with the I6 and 42RE would do that occaisionally when my fluid was about 1qt low as well, like dracer69 said. After I brought the fluid level back up to full, it went away. Be aware, the dipstick can be misleading...... i thought mine was full until i took a real close look at it and realized it was low.
Don.
 
Do the whole tune up, including fuel filter, throttle body cleaning, run some injector cleaner through it, etc. I neglected my fuel filter recently, and that caused some seriously bad running (and poor power probs, which degraded so slowly I didn't notice them until they were eliminated by a new filter).

Bob
 
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