Hey all, I just joined this forum after lurking around for a while for some different questions.
Anyways, I have a 2001 Grand Prix GT with 99000 miles on it (92000 on it when I got it in January). Sometime in March, I decided to replace the water pump/power steering pump due to a whistling/bearing like sound which actually turned out to be a vacuum leak in the crankcase due to missing an O-ring around the PCV valve (somewhat self inflicted.....I don't think there was one inside of the PCV valve housing when I replaced the valve so I never put the O-ring back on). After the install was done, I seemed to notice that my higher RPM shifts would hang between gears, IE shifting from 2-3 at 4000 RPM would cause the engine to hang at 4000 RPM for about 2/3 second or so before it would drop into the next gear. About a month went by, and it started getting worse, with the P1811 code getting thrown and even part throttle shifts and even part throttle acceleration getting poorer, especially when the engine was warm. I finally noticed my huge vacuum leak (and proceeded to kick myself for being such an idiot) and figured things would get better, but it still hasn't been nearly back to normal.
I've been trying to figure out exactly what the problem is. I replaced the TPS, tried to find any other vacuum leaks, etc., but in the end I still have the shifting issues when the car is warmed up, with low/part throttle shifts still clunking into gear when the transmission is hot and an occasional P1811 being thrown.
I know the PCS or valve body could be to blame, and I know that installing a shift kit like the TransGo kit could fix my problems for a while, but I want to make sure I'm not missing something important. Is there anything I could have bumped or disconnected when I did the water pump/power steering pump job? The only problem during that install is that I accidentally removed a front engine cover bolt which I replaced (don't ask, not one of my finer moments), but all in all it was a pretty simple job that I don't think I could have screwed up.
My thoughts:
1) Pay to replace transmission or the PCS/valve body parts that could cause the issues - EXPENSIVE
2) Try to replace other miscellaneous sensors/parts that could fix the issue, such as the cat, MAF, etc. etc. - EXPENSIVE if I don't get it right on the first try, plus not going to help a hydraulic issue
3) Install the TransGo kit and the fluid and hope for the best - CHEAP and easy, but it's still not going to fix the underlying problem
Sorry for the long ass post, and for coming across as a complete mechanical idiot. I'm actually pretty good with these things, but every time I work on this car I seem to have one brain fart after another and apparently mess something up.
If you can think of any suggestions that would apply to my issues, I would really appreciate hearing them. Thanks for reading!
