Need help.....I put a 5.0 efi from a 90 mustang and everything was fine. I had the battery disconnected for a month at the upholster. I reconnected the battery and started the car and it went to full throttle. What would cause this?

 

Stuck throttle... thats it.. check your tb. Bet it's open. Find out why

 

TB is closed (at idle)

 

Then it can't redline...

 

but it did.......

 

It reved up.. but it can't redline. Not if the TB is closed. The iac fully open might get you to 2500 rpm but that's pushing it. When you start it what rpm does it go too? I'd the TB remains closed it can't hit redline. Unless you unhooked every vacuum line. Held the iac open. And then still probably wouldn't hit redline.

 

OK.... I guess redline was the wrong word to use. I don't have a tach. but would guess the engine goes to 2500+ at start. I changed the TPS, checked vac. hoses, whats next?

 

5.0 efi is not my strong point (because I've only had my hands on a couple) I know the tps causes weird issues so a relearn might help. Only other thing I could think of is iac.

 

Intake leak will cause this as well. What we have done is spray a flammable aerosol around the intake to see if the gaskets have failed or a hose has cracked.

The next question will be is it running rich or lean. Rich will guide you to a problem with the TPS or another sensor and lean is too much un-metered air..

Good luck..

 

with the rpms so high it will not be possible to check the vac. with a flammable. could it be a problem with the computer?

 

How high does it rev to? I'm assuming that it's under 3000...

 

What? Too hight rpm to test with flammable liquid???

And yes it could be computer.. but it can be alot of other things also. Don't start pointing at components unless you have a reason to suspect it's failed. Can't stand mechanics that throw parts at cars trying to fix them instead of diagnosing the problem and fixing it right the first time..
He said he has no tach