1998 Trans Am
freshly built 4L60e
TCI converter (mostlikely the problem) was sent back to TCI over the winter to get cut open, inspected, and restalled.
There is only about 200 street miles on the rebuilt trans and converter

Everything in the car is fresh. I got 13 passes on the rebuilt trans and converter.

On the 14th pass the converter flashed to 4000, and then the car would not accelerate as if the motor was hurt. The car then slowly pulled up to 5000 rpms and shifted into second, and it did the same thing as if the motor was down on power for the next shift. I have my shift points set for 6500 and had no problems with the prior 13 clean passes.

It almost seems as if the the trans was in 3rd gear when I left the line (but it wasn't cause it shifted) or maybe the lockup clutch is locking right when I leave. This happened 3 times in a row before I loaded up and went home.

Prior to the last pass I stopped way back in the staging lanes and did one of those ******* launches in the lanes and the car was fine, although it was spinning the tires. The car also doesn't act any different while pulling a burnout, but I am also not at WOT during the burn out.

I also ended up having to drive my car home from the track cause a friend of mine broke. My car drove perfectly fine all the way home. The trans shifted normal, and the lock up clutch worked as normal, and the moto rwas not down on power at all.

BTW, when I do a burn out I use a line lock and start off in 1st gear and shift the car into second manually during the burn out and hold the rpms around 5500 during the burnout.


I didn't change anything in the trans tune all weekend. I do have a HP Tuners log of the problem but unfortunealy I wasn't logging line pressure or TCC. There are also NO trouble codes.

What the hell is going on ? Any ideas ? Anyone ever have the same problems ? TCI converter ? Trans ? ECM ???
I've heard many bad things about TCI converters.

 

Well all of the things you mention are possible and more, But that would be a hard on to diagnose without actually feeling it happen. I will say in the case of converters and transmission generally the rule is either they work or they dont but not work sometimes

 

Thanks for your response. I thought the same thing about converters.

When the car leaves it converter flashed to 4000 and then it sounds like the motor starts lugging or straining like there is more load on it.

I am going to pull the trans pan tonight and see if there is anything in the pan. Then I have a friend with a fresh Vigialty converter I am going to try, as long as there isnt any pieces in the pan.

 

anybody else ? Anyone with experience ?

 

Definitely start with the converter. Add me to the list of people that think the TCI converter is suspect at best.

Also, take it out and make a WOT pull while recording the TCC. It is possible that it is locking up at WOT, but.... it would want to pull real hard on the big end if that were the case IMHO.

Get back to us when you have had the pan off and we'll take it from there.

Good Luck

g

 

Thanks for you response Ratchthed !


I pulled the trans pan off last night and I didn't see anything out of the ordinary. No big chunks or anything like that. There was hardly any real fine metal on the magnet. There was a slight silver tint to the transfluid but I felt that is normal. My trans guy said that could possibly be aluminum from the converter.

Tonight I am going to change the converter and see what happens. If I have time I'll try and make a hit on the street, but most likely I'll have to wait til the weekend to get to the track.

When I get back to the track I'll try and log as much trans info I can.

Later tonight I'll try and post up a log of the bad pass from this weekend.

 

update

I changed the torque converter lastnight.........

The torque converter is not the problem. It is still doing it and now it may be worse. The problem happened to me just driving it normal on the street, this time it lugged the motor at 3000 rpms instead of 4000.

The converter I swapped seems to be tighter than my TCI.

The problem is intermittent. (electrical ??) I tried launching the car in off idle 1st gear and it seemed to work ok. Then I tried stalling it up and put the shifter in 3rd gear and it actually launched but it still seemed a little down on power as if it may have been slightly lugging the motor but not as bad.

I'm gonna pull the valve covers and plugs tonight, and do a compression check just to make sure the engine is ok.

 

Update.

Things I did last night just to make me feel better.

Pulled plugs and did a comp test. 170 psi on all cylinders
Rockers were all good and tight.

Changed fuel filter.

Drove around with a fuel pressure gauge taped to my windshield, fuel pressure held at 60 lbs the whole time including when the problem happened.

Tried swapping out the MAF.

I still have the problem and it is intermittent.

 

Still having this problem.

Trans was gone thru and checked out. The problem could not be recreated on the trans dyno.

Trans shifts fine at the track when I manually shift the car.

 

Update for those following this thread. Looks like its in the tune.

https://ls1tech.com/forums/pcm-diagnostics-tuning/913026-car-feels-like-lauched-drive-3rd-gear-tune-problem.html

 

What if you just changed to a th350 and the first 4 or 5 runs it done great and then you stall up at the line and when you leave it just bogs down untill about the 60ft mark and then takes off like i shot it with nitrous.........I will not even do a burn out now.......