Very late shift hot Jeep

[SIPLOWGUY]

I have a 97 Grand Cherokee with a 4.0L. It has 47,935 miles. We took a trip to Philadelphia today and when I got off the Turnpike the trans shifted VERY late and then slammed into 2nd. It seemed on the way home it shifted fine in Philly but was the same delay coming out of the toll booth of the Outerbridge Crossing. This truck has been flawless in the 5 years I have it. Anybody have any ideas? I'm thinking of a trans service.

[szorno]

My daughter in law has a 95. It was acting a little weird, so I am going to start with the tranny service. if you have over 75-80k, do NOT do the pressure flush. Just drain and re-fill. In a high mileage vehicle, the pressure flush can loosen things that should not be loosened. Anyway, service it, and add a can of BG transmission treatment if you can get it. That may not fix it, but it will let you know there is something more serious if it does not. cheap fixes before expensive ones my Dad always said.
;)

[thesnoman]

Pay attention to tranny fluid color too. I suspect that it is cooking it. After drain and refill with filter change I would add a aux tranny cooler as heat is the number one enemy of any automatic tranny.

[wyldman]

Sorry to respond so late,I missed this one somehow until it got brought back up.

Your truck uses the Asian Warner trans,called an AW4.Not much really goes wrong with them internally.It's probably a bad TPS,which is very common,causing late hard shifts,most commonly the 1-2 shift.They also had some problems with the output speed sensor,but it would cause no upshift at all,and you need to shift it manually.

The trans service can't hurt,but it probably won't fix the problem.Older trannies,with mechanical governors,would get gummed up and sticky,and a trans service would sometimes cure the problem.This doesn't happen much with the newer trannies.

Your best bet is to take it to someone who has a good scanner,and look at the data stream.You can watch the TPS voltage in real time,and when the problem happens.You can also watch everything else engine and tranny related,and most likely find your problem.It may even have stored a code or two,to point you in the right direction.

Your truck should already have a fairly stout cooler.Fluid overheating was never really a problem on those trucks.

I would also recommend you stay away from any additives,as most of the newer trannies are very sensitive to fluid viscosity\lubricity,and adding additives can change this drastically.

[SIPLOWGUY]

Thanks Chris. I had a check engine light on after the kid at Costco put the gas cap on ****ed. The code reset but I will try looking for stored codes. My buddy was the Sales Manager at the Chrysler dealer when I got the truck. He told me all these Jeeps are trailer tow ready because all Jeep did with the trailer tow option was add the hitch. I'm due for an oil change and already have the filter and correct fluid. I'll let you know what I find.

[wyldman]

The Check engine light will reset if it doesn't see the fault (gas cap) for 20 or so drive cycles.You should still be able to see code history,and any pending codes with the correct diagnostic equipment.

Make sure when they look at the data,they only focus on a few parameters at a time.The less data you look at,the faster the refresh rate on the scanner,and the more accurate the data will be.If you look at all the data at once,then the refresh rate will be too slow,and you may miss a smal glitch in the TPS.Hopefully,you be able to spot the problem.

[SIPLOWGUY]

Wyldman, Trans is getting much worse. It now double shifts fron 1st to 3rd. After the RNC I'm going to bring it in for the trans. It is still under warranty anyhow. Thanks for your help.
Mike

[SIPLOWGUY]

Just an update: Trans was rebuilt in December. The valve body was the problem. The warranty company wanted to put a used tranny in but couldn't find a low mileage unit. So far so good!

[snowplowjay]

Scott if I am not mistaken there were LEMON issues on a batch of the 95 Grand Cherokees..................

I remember when my father had his 95' GC it was in for a few weeks because of the TRANNY ISSUES..............


Jay

[SIPLOWGUY]

Mine is a 97, any info on those?