1997 Pontiac Trans Sport transmission issues

[mrdctaylor]

I have a 1997 Pontiac Trans Sport minivan. I had the automatic transmission fluid changed at 50K miles (as recommended by SEVERE service schedule in the manual). I know have 86,000 miles on it and something is slipping/shuddering when it makes its final shift (around 50 mph). I just had the transmission fluid replaced (dropped pan, replaced fluid and filter--NOT a flush) and the problem seems worse now. I'm looking for feedback from anyone that has experience with these transmissions (or transmissions in general) as to what I can do. This is FRUSTRATING to have a transmission act like its going out with only 86,000 miles. I really take care of my vehicles and it is upsetting that they don't last. I also have a Toyota truck, and I think my next vehicle will be a Toyota too!

 

[mrdctaylor]

I should also mention that it is intermittent. It might happen several times in a row, but then not happen for awhile. I'm not sure what's going on.

 

[Titanium_Alloy]

It's nearly impossible to pinpoint transmission problem just from description. There can be a number of things from some minor stuff to complete rebuild. It might not even be transmission problem. There was one post on this forum where driver of Ford F-150(I think) said that he was having transmission shudder after ATF change although car was well maintained. After some time and few attempts to fix transmission he discovered that it was a bad ingnition coil on one of the spark plugs.

In a different situation I would say that you should try Lubegard Red. But in this case it might only mask the real problem. Unfortunately, in your situation I have to suggest that you take it into independent certified transmission shop. I've never tried them but www.atra.com might be a good start to find a shop closer to you. You'll probably have pay for diagnostics.

Regards,

 

[mrdctaylor]

I took it to a local mechanic that I trust today at lunch right after I posted the message. He said the same thing, basically. He said it *could* be an ignition problem. He drove it and *thought* it was the transmission but couldn't be sure. It isn't acting up enough right now to show up on his scanner, so he recommended not doing anything for now and to bring it back in if it gets a little worse. He doesn't want to do unnecessary repairs on my vehicle. It is good to have an honest mechanic.

 

[Matt_S]

This sounds very familiar. Is this the 4T65E transmission?

Anyway, I was having a similar problem. I have a 2000 Monte Carlo with the 4T65E. Mine was creating a pulsation in the engine RPMs, like you were taking your foot on and off the pedal. It turned out to be the solenoid that controlled the torque converter lockup. In my case, the dealer fixed it under extended warranty, so I have no idea of the price, but I'm sure it didn't involve any extensive rebuilding of the transmission. The car has been fine since the repair was done.

BTW, I also thought I might be looking at a fuel or ignition problem at first, but nothing I did in those areas panned out. The dealer was able to diagnose and fix the problem on the first visit.

 

[motorguy222]

I don't know if this will apply to the vehicle in question or not but who knows? I had problems several years ago with a GM car.It acted like the trans. was slipping.I had the fluid and filter changed,didn't help.It still felt like the trans. was slipping.Not long after this,the alternator went out.The alternator was the problem the whole time.I figure that the alternator was putting out less voltage than needed but not enough difference for the light(no gauge)to come on.This was causing the electrical system to go wacko which made the car run funny.After a new alternator was put on,the car ran great again.Maybe you should get your charging system checked,it may pay off.

 

[mrdctaylor]

Yeh, I think I have the same transmission. I've hear that the TCC solenoid often goes bad on these. I'm hoping that's all it is--I've heard its not that expensive.

 

[GT Mike]

You have the exact transmission and exact problem as my '97 Grand Prix. The EPC solenoid is sticking. Mine acted up real bad and then fixed itself. I asked my expert transmission guy what it was and he told me the EPC got hung up with some crud that got stirred around in the ATF when it was changed (or in my case flushed...Yeah I know.). The correct fix for this is to buy a new loaded valve body right from GM. The EPC wears out the bore in the valve body where it slides into, and eventually won't provide a good seal anymore. The transmission does not have to be removed from the vehicle...Only the side cover removed and the valve body replaced.
It's up to you, but this is also a good time to install a shift kit. The TransGo/Gil Younger 4T60E Jr. kit is a nice addition to these transmissions, and they only firm the shifts up a little bit...It's not tire barking harsh like the ones available for other transmissions. It does help them last longer. I have one in my car, and it feels barely noticeable around town, but at WOT is nice and crisp.

 

[mrdctaylor]

Hehe. A shift kit in a minivan. That'd be sweet! Seriously, what do those things cost? I'm not really sure what a shift kit does exactly. How many miles did you have on your transmission when you installed one?

Right now, I haven't noticed that transmission doing it that badly, but I really haven't been driving it that much. I guess we'll just sort of "let it go" for a while until it starts acting up worse. My mechanic said it needed to do it a little more consistently and for the problem to last longer than a split second in order for it to show up on his scanner. He wants to make sure the problem is pinpointed instead of guessing and possibly ending up replacing stuff unnecessarily.

DT

 

[tmorris1]

GT Mike is describing exactly what happened to my Pontiac Montana. The torque converter would lock and unlock going down the road. Any slight incline would cause the RPMs to jump up. It was fixed under warranty with a replacement valvebody. It also showed some transmission codes for a slip or long shift I think. If I remember it was about a $900 bill without warranty.

 

[GT Mike]

Actually, the EPC controls line pressure. When mine acted up, a couple times it shifted like so much slush, and also shuddered real badly taking off from a stoplight. The next morning, it must have gotten stuck the other way, because it darn near shook the dash right out of the car! About 15 miles of sledgehammer shifts. A little tamer and I could have lived with it, but this was just nuts, and I knew not good for the transmission's internals.

If I recall, that shift kit (actually it's just a valve body improver kit) is under a hundred bucks. It just makes the shifts a little firmer and more noticeable. Since your vacuum modulator controls line pressure in relation to throttle angle, it doesn't really do much at anything but WOT or close to it when there's little vacuum.

 

[mrdctaylor]

I finally got it into the transmission shop, and guess what. It isn't the transmission. It finally threw some codes and it is cylinder misfires. So I'm taking it back to my mechanic later this week for a tuneup. Hopefully that will take care of it.

 

[Ugly3]

Finally a solution that does not require a rebuild. Sweet!

 

[mrdctaylor]

Yeh! You're telling me! It is in the shop today. I will report back once I get it back to let you know what he did and if it fixed it. I'm keeping my fingers crossed.