I got a 91 Firebird with the 3.1 engine and not sure what tranny but its the factory one. When leaving a light and runs great off of 1st then 2nd gear seems to like pull back for a second and then engages. At some times it doesnt do it at all. If recently swapped the filter and added 5 qts of fiuld and it shifts much better but still just trying to figure out why 2nd gears does that. Added Zmax stuff to tranny yesterday and hopeing it helps.

 

You have a 4L60 (also known as a 700r4) tranny.

It is possible that you have an ignition problem that causes low power under heavy load and not a tranny problem.

 

Now when you say ignition problem where do I look and or start to figure this out.

 

any input

 

Cap and rotor, plugs and wires, to start.

Specifically, I have had problems with the coil on these engines. They get hot and burn through the insulation causing misfires.

Run the engine in the dark with the hood up. You will be able to see spark tracking to places it shouldn't be going...

 

Hey KrisW, Well something weird happen yesterday. 2nd gears shifts under 2000 rpm but it didnt shift til it hit 3200 rpm. I notice this when the car has been sitting for a day, but once its warmed up it drives fine. I replaced plugs, cap, wires, but didnt change the coil. I was wondering is there a vaccum line running to out transmission and or a sensor also there. Maybe I got a vac leak or the sensor is bad or dirty. No CEL so not sure what.

 

Not having a check engine light is what makes me lean towards ignition misfire. Put your engine in the dark and watch it run with the hood up. You need to see if something is tracking somewhere.

There's no vacuum to the transmission, just the TV cable, and it doesn't change. The sensors that the computer uses don't effect your transmission shift point. You have a mechanical governor in your transmission that does that. It's on the side of your transmission and it usually has a bail clip over it to hold the cover on, like an older master cylinder on an old car. Sometimes they get stuck...

 

Im going to drive it home from work and then lift the hood and see what happens. Thanks

 

Well Kris I got home last night and was in the dark and look under the hood and found several sparkly lights going on. The heat sheilds that covers #1 and 3 spark plug boots where show sparks so I removed them and it was good for the drivers side but the passenger side the coil was sparking also so I replaced it this morning and tonight again ILL check. The engine runs much smoother now but I still feel a little pull on 2nd gear but much better then before. Thanks alot and any other info would be great.