5.0L troubleshooting help; Idle when hot issues.

Originally Posted by SnakedMark8

If you worked with the Ford EEC stuff before then you know that with the EEC IVs when you increase the FP the processor will learn the change and then adjust the injector pulse rate to back it back down.

But that is part of the issue I think - at idle the pulse width is already so small, a reduction by the EEC to correct makes it even smaller and mixture control becomes coarse. IIRC, by raising the pressure 5 PSI, the pulsewidth becomes so small, a .1 millisecond change can swing the AFR by some 5%. That's equivalent to swinging from 14.5:1 to 13.8 or 15.2 in one cycle. Throw in the mods he's done that the EEC must adapt to and this could cause some of the symptoms he is experiencing. The same effect applies if 24's are installed with no changes - the EEC tries to pull pulse width and it runs like crap at idle.

Originally Posted by SnakedMark8

According the Ford manual in front of me 30 - 45 psi is the norm. I personally like to keep it at 40.

I thought that was the operational range with manifold-referenced fuel pressure while running, i.e. - down to 30 as the FPR reduced rail pressure under vacuum. It's been a long time since I read all that though.

David

On second thought, the best advice might be to contact a local shop that can create a custom program for you. I'm thinking a quick answer is not going to give you the results you expect.

I appreciate everyone taking the time to reply. I checked and double checked fro vacuum leaks and found nthing. If reprogramming my comp is where I need to go that isnt a problem. I just have a hard time understanding why the motor idles sometimes (low), rarely high, and mostly hunts and then dies. Sounds like a sticky IAC but I have swapped it and replaced it with no help. frustrated, Chad