C5_Pete

iTrader: (8)

Is there a way to view transmission performance on my EFI live?

Last time out, the car ran great, but the trans was shifting several hundred rpm after the programmed shift points.
This time out, the car wouldn't even come off the trailer. No movement in any gear - forward or reverse.

I'm just wondering it there's any troubleshooting I can do with EFI live prior to pulling it out to fix the issue.

Thanks

mrvedit

No tuner will help you with no gears at all.
Even if you disconnect the electrical connector to the trans, you would have reverse and 3rd gear.
Assuming the flexplate and converter are bolted up, you have fluid and the shifter is moving the trans shift rod, it is almost certain that your pump is shot. Here is a test:

With engine off, check your trans fluid level. It should be above the hot-full line. Start the engine and check the fluid level again. If the pump is working, it will go down by about an inch.

C5_Pete

iTrader: (8)

Thanks for the reply. I should have mentioned I have a C5. No dipstick.

I can lift the car and check the Trans fluid. I checked it at the track, but the engine wasn't running. It ran out all over my arm. I forgot it needs to be running to check.

mrvedit

The pump can also be tested by disconnecting the lower (*) cooler line at the cooler and checking/collecting what comes out.

* Note: Not absolutely sure, but I think the lower trans cooler fitting is the pressure line from the pump and the upper fitting is the return.

Dynamic396

Yes, this is accurate...

C5_Pete

iTrader: (8)

Perfect. Thanks.

I'll report back.

C5_Pete

iTrader: (8)

Cracked a fitting near the cooler and fluid slowly came out.

Unscrewed the plug that's just above the shifter attachment and attached a pressure gauge.

About 50 psi at idle and goes up to about 100 as I increase rpm.

Next step, pull the trans out.

mrvedit

50 psi is the stock pressure and certainly enough to give your forward/reverse.
Wow, so have line pressure and neither forward nor reverse works. Forward and reverse have very few components in common; pretty much only the input and output shafts.
Not to insult you, but you are sure your shifter is working and your half-shafts aren't broken?

You might PM member RonSSNova for advice on removing/installing the trans in a C5. Good luck!

C5_Pete

iTrader: (8)

Not insulting at all. Even the most experienced mechanics overlook things from time to time.

It is definitely not a half shaft or output shaft. It's not the shifter or linkage assembly either.

Ron and I talk every once in a while. My old car was a very similiar build to his.

I've removed and replaced the driveline in many vettes, I've just never messed with an auto transmission before. It's like voodoo to me.