My 95 firebird 3.4L just started not shifting into 4. It does not feel like slippage all of the other gears work and shifts are fine and have been. 106k miles on the car no mods daily driver. No check engine light or codes. I'm thinking it might be the solinoids. Does OBD have tranny codes? This is not OBDII. Changed the fluid two months ago. Any advice from the experts would be appreciated.

 

The other day i had similar problems with my tranny not engaging 1st (or so I thought). Talked to my tranny builder and he said straight away the solenoids.

He recommended scanning with Tech-2 to determine what Command-Shift was being requested first. That would eliminate the tune.

He took the sump off and noticed a few things. The tranny was overheating due to incorrect oil cooler being fitted. This caused venting of fluid and in turn crappy shift points. It also caused poor line pressure resulting in 1st and 2nd engaging at the same time!

He replaced the solenoids, oil and acumulator (as the plastic accumulator head was cracked due to overheating) with an aluminium one.

All fixed. Wheelies from 1st again.

I know this si not exactly the same problem you have but you may be able to glean something from it.

Scan it, then take the sump off and measure voltage across the solenoids.

 

Yes, I think mine is overheating too. I topped it up with a pint more fluid and it is working fine for now. Of course it is since I ordered a solinoid master kit. I don't have access to a tech 2 for with out going to a shop. If it does it again, i will just take it in and have them work on it. Any other comments would be appreciated.

 

It should not be your solenoids. Here is how they work. There are 2 of them, "A" & "B".
With the shifter in Park, Neutral, reverse, 1,D and OD, both "A" & "B" are on (1st gear). Whether you manually place the shifter in the next three positions or let the tranny shift automatically; 2nd is "A" on, "B" off. D (or 3rd) both are off. OverDrive "A" is off, "B" is on. So, you can see if "A" is bad, you will have 3 & OD only. If "B" is bad, you will have 2 and 3 only. If both are bad, you have 3 only.
If memory serves, none of the other 4 solenoids control upshift to OD.
There is a TCC (lock-up) sol. that will not lock the converter if it's bad but you say no OD.
Pay the $$ to get it scanned, you can easily spend $100 replacing this and that and still not solve the problem!
Good luck, keep us postes!

 

Well, I put a pint more transmission fluid in and it has been working fine. I'll wait until it starts messing up again and have it scanned. I think that they do spontaneously heal sometimes. Thanks for the help. I'll keep you posted.

 

Well, it went south again and I put the solinoids in and it is working fine for now. I'll see if it keeps on working or if it was just the fluid change that made the difference. I am noticing the torque converter lockup working again and it shifts all gears fine. I'm keeping my fingers crossed. This was actually a pretty easy job.