I got my tranny beefed up here with a local guy and the tranny felt good driving around except at half throttle on the 3-4 shift, as it shifts, it locks up, and unlocks real quick.

what could that be?

pat

 

If the PCM sees excessiv converter slip it will unlock , what you need to do is check for codes and if there are none look at the data stream and see if the converter is actually being comanded on a off like that

 

Ok,
we checked for any codes and there weren't any.

pat

 

Well hmm theres not really very much to lockup , there the lockup solenoid and the PWM solenoid Honestly I really cant think of anything that would cause that, You may want to do this though if you have access to a good scanner or tuner that can look at the data stream you might try and watch and see if its being commanded on then and going off buy itself even though the pcm still says its enabled , or wether the PCM is actually comanding it back off, I would do that first and watch the data stream and see what the trans is being told to do, that could help you determine where to start looking

 

Did anyone attempt to tune the shift points and TCC lock up speeds? If so, they could have misadjusted the 3rd gear TCC lock up point to overlap the 3-->4 shift points. Typically results in what you are experiencing.

Give us more info, has the vehicle been tuned, what else was changed, why did you get it beefed up, etc ... ?