Same car, new problem. Installed new PCM and test drove car several times with great success. TCC works great. However, went to back car out of shop next morning.......no start!! I have spark, fuel pressure, crank RPM's on both 3X & 18X sensors, a good Cam sensor waveform at sensor and PCM......but ...

ECM solved the problem. Very low slip RPM's (0-125) with very steady duty cycle & no surging.

The car is pretty good condition.... but now I'm leaning more toward an ECM than a TCC or solenoid. I can lock & unlock the TCC with the scanner & problem is not there & no slip RPM's (TCC will go to 99%). If I let the computer control TCC engagement, it only goes to about 35-55% duty cycle, never g...

I typed the wrong engine size in my first post.... it is a 3.4L. Now I have created a new problem, how to isolate the ECM and wiring, or trans repair, or complete trans replacement / torque converter. Customer is willing to pay more diagnostic time. I have some tests in mind, but any thoughts?

I think I may have answered my own question. It appears that the problem is the TCC solenoid or TCC maybe not holding at partial lock. The surge only occurs when the TCC is applied, & I'm getting slip RPM's (100 - 600) that are very erratic during the surging event. If I completely lock or unlock th...

2001 Pontiac Grand Am w/3.4L surges; sort of like a miss climbing hills & acceleration. Seems to only happen when torque converter is locked. I also seem to reduplicate at 1.20 - 1.35 V on the TPS but only while driving. Only codes in memory was P1122 Tp circuit (I replaced TPS just to eliminate.......