Someone else's car. Car overheated a couple times. I replaced the water pump and water elbow that is above water pump and a common issue. Some time after repairs, car started to develop surging when TCC is locked. Will do it at a wide range of RPMs and speeds and seems to only do it when TCC should be locked and you are lightly accelerating or going uphill, etc. Once unlocked, it seems to shift ok. On occasion, it seems the car fails to make it back to 1st and will clunk when taking off which suspect is bumping back to first. It will also, at random, shift very harsh, then just shift fine.
The odd clunk at take off and harsh shift is VERY random but the surging is very consistent though the severity seems to vary some. I personally just drove it 300 miles and just work with it to keep it from oscillating but I usually just add more pedal to totally unlock TCC.
Before we go and tear the trans all apart, I am wondering if there is anything else I need to be checking? I did do some base level testing while plugged in and TPS looks very smooth, no wandering. I did not really look at MAF too much. I am also wondering about any simple wiring issues? I was going to go plug into a tech II to observe the TCC duty cycle and slip but maybe something else?
I have read some considered a misfire but I cannot really lean on that too much as I would think the ECM would find that. It otherwise runs great. WOT pulls as it should through all gears.
Woops, 2006 grand prix, 130k miles. no codes
