Thread: Possible Trans Issue 1998 GTP

Over the last few months, I've noticed that when I'm in third or fourth gear and I give some moderate throttle, I feel some sort of jolt from the car. It's a pretty hard jolt, enough to make friends wonder what's wrong with my car. It's strange, because if I'm driving at 55 on the highway, and I give the car 1/4 throttle or so, it's almost like the transmission is unlocking, and then locking back up really quickly, and it will do it about every second until I give more throttle to kick the trans down a gear. I have this issue in third and fourth gear. I don't think it's any kind of slippage, because I've done a full throttle pull to about 130MPH, and the trans does not slip at all in third gear.

My car is a bone stock (for all I know) 1998 GTP with 102,000 miles.

kinda sounds like your 4 th gear hub is worn out. or wearing out. what your feeling could be it slipping in and out of over drive.

Also, speed limiter is 127 and 110mph in 3rd select with factory tune.

It also is very bad for the transmission to shift into 4th at those speeds, just as a fyi.

Scotty, if my car does the same in third and fourth gear, could the fourth gear hub be causing the issue in both gears?

I had the car up to around 130, so maybe 125. I was showing a friend that my gtp was faster than his V6 Camaro, but another time I had 3rd selected (this is when I was testing the trans for slippage) and I hit the 110 limiter.

But basically, at moderate throttle and when the trans is fully locked up, it almost feels like the car decides to downshift, but then changes its mind within milliseconds, causing the jolt.

I'd hook it up to a live data scanner and be watching tranmission related pids/tables. It might be an issue with the TCC.

Maybe even a stored code on the transmission side. But not everyone has a scanner like this.

I don't own a scanner or really know anyone with one. I really just want to fix it for peace of mind. Other than this, the car has been more reliable than anything I've owned.

I'm just not 100% positive that it's mechanically worn parts. Like you mentioned, I'm hoping just a solenoid or something stored in the computer.

Scotty may be on to something though, because sometimes when the car shifts into fourth, there can be a delay. It could be two separate issues, but if I can get the jolting one fixed, that's all I care about for now.

best to scan it, make it act up, then hit autozone, dont turn the car off, ask them to scan it for codes, its free. if you have a pending code it will clear when you turn the car off, so leave it running, bring a guard dog or friend to watch the car.

Originally Posted by Scottydoggs

best to scan it, make it act up, then hit autozone, dont turn the car off, ask them to scan it for codes, its free. if you have a pending code it will clear when you turn the car off, so leave it running, bring a guard dog or friend to watch the car.

Yeah, I have an AutoZone nearby. I'll see what I can do (when I have time) and post my information back to the forum. Thanks for all of the suggestions guys!