2004 Grand Prix GT the lock up torque converter locks hard at around 2000 to 2500 rpm on normal accelleration. Problem in intermittent with no pattern and engine temperature doesnt seem to be of any effect. Trans fluid and filter changed but had no effect. No bad stuff in pan at change. Engine runs fine, not engine performance problem. What controls TC lock up and how hard it locks? Trans shifting feels fine and normal other than the big bump of the lock up in first gear. Any ideas? Thanks!
Lock up TC engages hard on acceleration
- Thread starter dearmond
- Start date
Trannyman95
Transmission Expert
The best way to verify what is going on would be to have someone scan the car and spend some time driving it diagnosing what is going on. The pcm controls TCC apply rate and should never feel firm as it always wants to see a little bit of slippage giving it a smooth apply. TCC operation is not hydraulically possible in 1st gear as it gets its feed fluid from 2nd gear apply fluid so if it is really coming on in 1st gear then the TCC apply valve could be stuck which will eventually cause burnt fluid and bushings inside the transmission but this is a very rare occurance to see and doubt it is that drastic in your case since it is intermittant. You could also have a poor working TCC solenoid or sticky TCC regulated apply giving the harsh feeling and this would require removing the valve body for an inspection or replacement.