1992 Lumina Tranny Problem

[mrsurfer]

I have a 1992 Lumina Euro with a 3.1L V6 and an automatic tranny.
When the tranny is cold and in drive it feels like it's slipping when you go to accelerate. The engine revs climb, car does not move then it seems like tranny builds up fluid pressure and will engage slowly. The problem appears once in a while and I'm not sure if it's weather related ie cold.
Had the car checked by a tranny shop, typical it wouldn't act up. They scanned the car and found only the following engine codes set:

Code 23
Code 35
Code 43

Anybody have suggestions as to what may cause this symptom?

Thanks,
mrsurfer

[dwalmop]

Not sure about the tranny, it's probably on it's way out. I'm assuming you checked the fluid level.
As for the codes,
23 = Manifold (intake) air temp, could be faulty MAT/IAT sensor or wiring
35 = Idle speed error
43 = Knock sensor problem

[mrsurfer]

Yeah, I'm thinking the tranny is starting to fail. I did check the fluid level prior to having the vehicle looked at. This problem just started to happen when the temperature dipped. It doesn't do it all the time and as tranny gets warm I cannot recreate the condition, could it be a sticking piston?

[mrsurfer]

This slipping problem I described now appears as you slow the car down and it starts to downshift if you press on the accelerator it seems like the tranny is stuck between 2nd and 1st gear then all of a sudden it goes into gear. Once car is hot it does not have this problem. Could this be a faulty vacuum modulator or do you guys think it's an internal tranny problem?

Thanks,
mrsurfer

P.S vehicle has 298,000 Km and fluid/filter were changed 2 months ago

[jeffcoslacker]

Bad modulator will cause it to flare on upshift, or possibly not be able to upshift at all without easing off the throttle, but wont cause the type of symptom you have, if I understand correctly. What I'm saying is you will have a problem on shifts, but not initial engagement. Your problem sounds more typical of seals that have hardened or cracked, allowing pressure to bypass when they are cold and hard. As fluid and /or ambient temp increases, this will allow them to soften somewhat, so they seal more effectively. Same thing caused the rack and pinion steering issues with some GM models in early FWD years. The problem was actually a soft metal that scratched easily in the rack, but the seals eventually couldn't conform to these irregularities when cold in the morning, allowing fluid pressure to bleed down enough to keep the unit from funtioning until the fluid and seals warmed up slightly. The colder the ambient temperature, the worse the problem got. You may (?) want to try a seal conditioning product like Seafoam or Trans-X in it, it might buy you another year without repairs. Has worked for me before.