Electrical Gremlins

Unmrkd · #1 01-19-2010, 10:55 PM

OK Guys & Gals, I need some assistance on this one. I have been "Freshning" my '89 SCHP for the past three years and finally turned the key on the rebuilt stock 306 this past weekend. It fired right up and upon initial warm up idled right down just like a new car. So long as the clutch is depressed everything is terrific. The engine check light did come on and stay on right after starting. I have not had a chance to get a code checker yet.

Now for the "RUB" - upon release of the clutch it will either die or immediately go to 2300 RPM running rough and stay there. "ALL" engine sensors are NOS. The exhaust is NOS Ford from the heads to the tip of the tail pipes. All harness are unmolested and are the original from this car ('89 5 speed configuration). Computer is an A-9L (swapped with another good A-9L and have the same exact problem).

I have replaced the clutch/starter safety switch (hooks to the clutch pedal swing arm) and the neutral switch (on the transmission) with no change to the problem.

If anyone has some good ideas as to what the problem might be it would be most appreciated.

woodsideg · #2 01-20-2010, 07:13 PM

sounds like it's time to pull out the old electrical manual and start tracing and chacing to see what all is on that same curcuit than start alimiting a see what goes. this curcuit should not afect the running but start only! all so check the ingiton switch to make sure it's not seperating

Unmrkd · #3 01-20-2010, 11:05 PM

I got a tip from a fellow that had heard of the problem several years ago. The O2 harness wire pin positions are critical. I replaced the harness with a new one that was supposed to be correctly configured for a '89 5 speed. Looking at the old and new O2 harness connectors there is one wire positioned oppositely.

A repinning of the new connector this weekend to mirror the old one and we'll see if that does the trick. I just love electrical problems - I live for this!

woodsideg · #4 01-22-2010, 12:00 AM

sounds like a game plan good luck

NoDrama43 · #5 01-22-2010, 11:29 AM

Quote:

Originally Posted by Unmrkd

I got a tip from a fellow that had heard of the problem several years ago. The O2 harness wire pin positions are critical. I replaced the harness with a new one that was supposed to be correctly configured for a '89 5 speed. Looking at the old and new O2 harness connectors there is one wire positioned oppositely.

A repinning of the new connector this weekend to mirror the old one and we'll see if that does the trick. I just love electrical problems - I live for this!

wow....I never thought of that one. My 92 CHP harness was replaced also as it had been hacked by Ricky Racer so I replaced it as well. I bet it had the same issue. Let us know if you get this one solved so I can print this thread for my tech manual.....

Unmrkd · #6 01-24-2010, 05:37 PM

I swapped the old harness back in the car and it works great!

It starts and idles correctly and revs smoothly. The brakes have not been bled so I have not driven it yet. We all know how important brakes are - don't we NoDrama43????

I do still get a check light after start up so I'll get that checked. I'll also repin the new harness.

The harness or the '87 - '90 5-speed is definitely unique. Lesson learned, just because the connector and harness "Appears" the same and plugs in the same receptical dosen't mean its the "Correct" one.

NoDrama43 · #7 01-24-2010, 06:16 PM

good news Gregg. I will definatly keep it in mind when I work on those year cars.

sspanthony · #8 01-26-2010, 06:49 PM

I knew you could do it Gregg; Great Job !