Gtp transmission problem - YouTube I'm pretty sure it's the TC locking and unlocking but I would like other opinions in the video I was going up a very slight hill with the Cruise on at 60 miles an hour .the big jump in RPM was when I touched the brake to turn the cruise off. I'm wondering if you could be in my tune because it seems like it takes way more throttle then it should for it to downshift out of fourth gear and same goes for it to get the TC to unlock using throttle. Car shifts 100% other then this. Sometimes it's slightly worse Maybe 500rpms instead of 300
Need to monitor slip speed with a scan tool. Should be close to zero. Then lock the converter to 100%, see if the fishbite feel goes away.I've replaced the converters and solenoids for this issue. Hope this helps. Phil.
Scan tool can tell you if the converter its self is slipping or it is in the transmission. I would lean towards the TCC solenoid failing. If the clutch was gone, there would be constant slipping. I destroyed a 4T65E torque converter with a turbocharged 3.8 engine and the symptom was a "smoother" slippage, not so much off/on like yours. Sincerely, David
All the shifting coils are under the trans end cover. Below is a picture. Mine is swapped into a Buick Century and there is not enough room to get the end cover off. It the Grand Prix it might be easier. Once the end cover is off, the swap is very very easy. There's just a little clip that holds the valve into the VB. It pulls out like a hairpin. In the picture you can't see the TCC valve clip, but you CAN see the clip for the EPC / Forcemotor valve. They are same idea. Sincerely, David
It's locking up when it shouldn't i juat tryed it and even going on a flat road it's locking up at like 38 mph and I noticed rpms were low so I gave it a Lil but of gas like I wanted to accel without it unlocking and it started doing it again
I have been lucky with my cars - no tranny issues yet K.O.W... you should be able to drop the cradle on the drivers side and sneak the side cover off to swap the solenoids - do them all if your in there , shift , pressure control , TCC , you may need to clear some other stuff out of the way but I know people that have done full teardowns/rebuilds through the drivers wheelwell without removal as well as drive chain/gearing swaps so it can be done in the car.... a member on here is one of the top guys in the u.s. for these trannys and sells parts like the solenoids on his site check out triple edge performance ( Dave Norris)
I have to say those trannys are pretty much garbage, I have had 2 GTPs and 1 a comp G, it works just fine until you add some real power, 1st GTP had simple bolt on's and was just fine, then had a built motor, head work lots of boost cam etc, blew the tranny before I even go to the track
not many platforms will take a lot of power on a stock trans , my daily has 217,000 on stock 4t65e with hundreds of low to mid 13 sec passes on the stock original trans - another 3800 fwd gtp I had went 12.2 @118 and I know a few that have broken 11's on stock trans then broken them.... if your looking to go 12's or faster on a 4t65 plan on spending 3 g's to beef it up , if your looking to go 10's or quicker plan on 5k , the 4t65 has been 8.6 @159 (ZZP)
It was an upgraded trans as much as it can go, it blew once before I bought it and then after I got it, I was around 375 at the wheels and yes Im very familiar with zzp as it was a car built by them in 05, this was pretty much my daily and I never even got to the track with some slicks to afraid of blowing the trans again as no one would warranty the trans.
I had a low 13 sec '01 GTP that I ran 130 passes or so on with 120k miles that my friend bought from me as a commuter and original tranny now has 165k+ miles on it. One wheel burnouts kill these trannies but other than that, I've always heard, and experienced, pretty good reliability... It would have been nice to change out those 2.92 gears/drive chain, but I never wanted to open it up.
Yeah, the GP trans are like glass once you start adding power. I got luck when I got my trans built for 98 GTP, I was able to get a 1" GMR chain set installed and when my stock diff went I was able to grab up a GMR Torsen Diff. I have hundreds of passes on it and still able to pull 1.70 60'. With my last setup, I was able to make 380 WHP, so I think mine is good to go. To the OP, Dave at triple edge does a great job and will be able to help you out. He knows a ton about these trans. Good luck with it.
