The transmission in my '95 z28 is having some issues with the fluid pressure after it's running for a short period. When I first start the car up, the pressure idles around 75 and will shoot up towards 200psi when pulling out of the driveway and it'll shift fine. It'll do near 250psi in reverse. A few miles down the road, the pressure will stay at 75 and not fluctuate at all, not even in reverse. It's almost as if the gauge is physically stuck at 75. The transmission slips on every gear change when the pressure is this low.

If I turn the car off and then back on, with the transmission still warm, I'll get full pressure back. If I put my foot on the brake and gas it lightly, the fluid pressure will go up to 150-175 where I'd expect it to be, then slowly fall back to 75-100 and then it won't go any higher, even if I shift in reverse.

I've had issues with the car slipping in first gear under heavy load for the past year, but the 1-2, 2-3, 3-4 shifts were always firm. The pressure would bounce a lot under part throttle, but I was told that was caused by the harmonics from the 10 vane rotor.

This low pressure issue just poped up out of the blue. Anyone have an idea what could be the problem here?

Thanks

 

Unplug the case connector of the transmission and see if it stays at max pressure. If it does, it could be something in the computer, wiring, etc. If the pressure still drops to 75 with the connector unplugged, it's most likely a bad EPC (Electronic Pressure Control Solenoid), in the transmission. I believe this transmission is quite a few years old, so it's a possibility. It's not a real big deal to change, either. Give me a call.

Frank

 

Thanks, I'll give that a shot tomorrow. I was afraid my pump rotor or slide may have cracked again but that's a little more catastrophic.

 

This problem seems to have gone away. I've been driving it for the past few weeks and it's been fine. I still have a strange issue with it feeling like it's slipping in 1st gear, but it's been doin that for 2 years now haha

Thanks again for the information, I still plan to pull the connector and see what it does if the pressure issue pops up again.

 

The "slipping" in first gear could be the converter.

Frank