KRPerf

I have been trying to help a buddy diagnose a problem for a little for a couple of weeks now. The motor will not idle, it back fires every once in a while, and just plain won't run right. The motor is a 5.0 HO out of a 90 Mustang. It is currently going into a '70 Mustang conv, fuel injection and all. The motor and heads have recently been rebuilt. The engine harness is a brand new piece direct from Ford. The computer he is using is an A9L. So far we have gotten virtually every code in the book. We have checked out every sensor and even tried changing the computer with no luck. We have double checked our grounds with no luck. If anyone has any advice, I would love to hear it. I am at a total loss. Thanks

90GTDan

Make sure you are using the HO firing order and not the regular 302 firing order that a 70' mustang would use. It will run with the wrong firing order but it will be terrible and wont idle. Its a place to start.

Edited for clarity.

mcfomco

Kinda what I was thinking. Sounds like the wrong firing order being used.

KRPerf

Thanks for the advice guys. Unfortunately, that was one of the early things that was checked. Everything on the motor is based on the new roller HO version: cam, distributor, computer, etc.

89Ford

how did you set the distributor

89Ford

maybe its a 180* off

mustnglvr

Have you illiminated the codes?

91hatchgt

I expect that it does have the Mass Air installed?

KRPerf

It does have a mass air meter and it is working properly. I have been trying to help him diagnose the problem over the phone which has been challenging. The distributor idea is pretty good, but I'm fairly sure he has that right.

89Ford

if the distributor is 180 off it will backfire im pretty sure and wont run