Fawking 3.1 powered GP's~!~!

[mfewtrail]

My cousin called me today and aked me to take a look at his 92 Grand Prix SE(3.1MPFI) and drive it a little to show me a problem he's having. So I drive the car and it seems fine to me until I start coming to a stop sign and slowing down, the car starts surging(idle drops and raises a little and also the voltage gauge shows a drop and rise), it seems like this only happens when the brakes are applied and/or if the blinker is on(draws it down farther) and the brake pedal feels weird also like some kinda vibration in it. A known problem on his car is the torque converter control switch and/or torque converter, his car is shifting into OD(?) around 45-50 and just feels like it has no power because of the early shift. I slightly mash the brakes and it shifts into the normal gear, my question is how do you exactly tell if its just the TCC switch or the TCC itself? and also what could be causing the surging? btw, the alternator and battery are new and have been load tested and are in good shape still. recently replaced parts on the car are the o2 sensor, plugs and plug wires(car was had the surging before the replacement of these parts). please put in your $.02, and thanks in advance for any info.

[Brian P]

surging is usually a vacuum leak somewhere

[Guest Anonymous]

The '89 GP I just bought was doing the same thing. I'm not sure which of these fixed it but this is what I changed.

 

1) Fuel filter

2) O2 sensor

3) Air filter

4)Connected fan to wiring harnass (someone had it wired into the ignition)

[Chinski]

Vibration in the brake pedal is probably warped rotors, especially in the front. Has the battry been disconnected recently? Could need idle re-learn done to it if it has.

[mfewtrail]

Just wanted to say that my cousin took the car to my uncle this afternoon so he could hook it up to a diagnostic scanner and see what all is functioning incorrectly and try to rule out the problems. I'll know tomorrow whatever is wrong with it, so I'll keep everyone updated and thanks for the input thus far.

[cmo1234]

I'll know tomorrow whatever is wrong with it, so I'll keep everyone updated and thanks for the input thus far.

 

Hey trail did you get to find out? Mine does the same sh*t and it gets annoying.. the surging that is. All my vaccum hoses look ok, no air hissing either so just wanted to see what else I could try. For some reason it seems to do it worse in reverse too while i have the brake on and slowly backing into a space and such, but its also random...

[Hairdo12]

check your idle air control moter on the throttle body. mine took a shit on me and the car would run great untill i stopped and it sounded like i was running on 2 cylinders (very rough idle).

[cmo1234]

Just saw this thread too that had some good suggestions too, I think my prob might be the EGR

 

http://www.w-body.com/forum/viewtopic.php?t=2942

 

Didnt find it before cause i did a search on surging not surge... duhhh go figure, hope this helps too

 

 

Still want to know what you found out though mfewtrail, just to have a second opinion

[mfewtrail]

ok, the surging was caused by the IAC on my cousins car, replaced it and no more surging. Also, the voltage fluxuating(sp?) was caused by a bad ground and a bare power wire that was touching the block(that couldn't have been to good)...also this was my cousins 92 GP, not my 93(its currently in pieces......not wrecked.....but restoring it and rebuilding the engine with some goodies)