68lsxc10

iTrader: (1)

I have a freshly rebuilt 4l80e with a 3000 rpm stall converter. The shifts seem soft and sluggish. I couldn't seem to make a difference with programming, so I checked the pressure. It has 70psi no matter what. Will not move up or down. I am going to get another epc solenoid ( force motor) and try that. Is there anything else I should check while the pan is off?

FLT

iTrader: (1)

Sounds like your issue might be with tuning. I could be wrong but the best way to see if the trans electrically is seeing the proper signal, is to check the amps going to the epc solenoid. You should see a swing between 5-0 amps. If not then you have problems else where. Even a dirty MAF or a bad TPS can cause this issue. Also did you install a shift kit with this trans? I have seen where guys leave the washer off the boost valve and the PR spring is unable to do its job. Basically it gets stuck in the sleeve instead of sitting on top of it. Good luck. Vince

68lsxc10

iTrader: (1)

Thanks Vince, I didn't build the transmission but a local shop did. There was no shift kit installed. I ran the current up and down with scanner software. I was told to also try unplugging harness on side of trans that would make pressure jump. That didn't make a difference either. I will check your suggestions because I really don't want to take this trans back out right now.

tptransmission

You can check the PR lineup by just removing the bottom. It is in the bottom side of the pump.

68lsxc10

iTrader: (1)

Thanks for the help guys. I pulled the reverse and pressure regulator valves, they were fine (no sticking or binding). I called a buddy that builds transmissions and he had another force motor. I put it in and fixed the problem. The brand new one in the trans was bad. Trans now shifts great, with a little tuning it will be perfect.