Just rebuilt the 4T65E tranny from my 01 Grand Prix. The transmission was falling out of lockup in the 50-60mph range. Tach was bouncing a couple of hundred RPMs. I bought a kit, new steels, new solenoids and a Sonnax TCC valve with scarf cut seal. I didn't replace the pressure control switch. I finished the job and reinstalled the tranny only to be dissappointed because the transmission wouldn't shift properly. I took it back out of the car, totally dissasembled the transmission but didn't find anything improperly installed. The only problem that I can think of is that I had attempted to improperly assemble the 2-1 manual servo on the first time around and scored the inside bore of the servo housing where the rod moves through the outer housing to contact the band. I didn't think it was that bad but the symptoms are as follows:
In drive, car moves forward normally until RPMs reach approx 1700. At that point I can here an audible sound "phtt" that sounds as though fluid or air is being released. The RPMs drop off and the car losses power. This happens again and again unless I step into the accellerator then the car RPMs go over 2000 but the car lacks power but will gradually increase speed. It delays shifting but I can let off the accellerator pedal slightly to get it to shift. I can reach a top speed of about sixty but it doesn't want to go much faster. It downshifts fine. I checked all of the lip seals for proper orientation while I had the transmission appart for the second time. Can anyone give me an opinion or advice?
