hooker52

OK I am having some driveability problems. I own a 89 ford mustang gt 302 bottom end with 351w heads. Heads have been ported polished and swriled . Also a msd 6al, blaster 3 coil and a E303 cam. Everything else is stock i.e. the intake, injectors and the throttle body, and no chip. I have a strange problem! Ill try to explain it as well as I can. If you have any ?s about abbrevations just ask. My car seems to be gettting too much fuel, and at the begining I could not pull the codes from the computer, get back to that later. When I drove the car it would lurch very hard off idle. the car idles about 1100 to 1800 with the clutch pedal out and the check eng. light would stay on constantly. My cats were glowing red I almost caught my car on fire once, and no its not the timing or the firing order I have checked and re checked! But when I depress the pedal the Idle would go back to normal. about 850 rpm. I did a lot!! of trouble shooting and found that my vref voltage was at about 3.5 v when it should be at 5. v. If you dissconect the large white plug close to the fire wall mounted to the upper plentum the v. goes back up to 5. v or if you connect that plug and dissconect all the assoiated sensors to that plug , tps, bp, evp, act, the v. goes back to 5v. I descovered a temporary fix though. When I jump the 2 connectors on the clutch interlock switch, located under the dash connected to the clutch pedal the wiires are red and lt bl in color the eng runs normally unless it is already warmed up. If the car is already warmed up then the idle skyrockets and the check eng. light comes on until I disconect the wires and then reconect them. Also The computer codes cannot be pulled from the computer unless the clutch is depressed or the r/lb wires are jumped or connected. The codes I pulled from the computer were 22,34,67,81 almot all having to do with the vref voltage. I hope all that makes sense. I have been strugling with this car almost every day for about a month, Im ready to go racing but thats kinda hard if ou got wires hanging everywhere like I do. If anyone need wiring diag. or how to test certain sensors I have it all feel free to ask.

Big Block Ford

I'm afraid I'm no help on this one but with luck someone will have some ideas.

__________________
Lance
71 429SCJ Mustang

big1

I have heard of a similar problem. Turn's out he had a bad ground. It's not much, but I hope it help's.

__________________
When in doubt :DON'T
Valley Station, Kentucky
Dream EXPression Racing
http://fordexp.freehomepage.com/photo3.html

hooker52

Thanks I wish you would have seen this post about a month ago. Thats what I found also. I just grounded it to the bat. neg terminal. I was missing the ground on the siginal return circut. but I dont know where the ground is exactly If you or anyone else knows where this ground is that would be great. Thanks

dawger989

Hey hooker my 89 GT has almost the same problem as you. I was wondering what you exactly did to fix it cause I would like to get mine runnin right too. I sent you an email but if you did not get it for any reason PLESAE email me at dawger989@netscape.net. Thanks. And anyone else that may know what the problem please let me know! thanks