Hi all, I'm bringing this problem back up after a few weeks of not messing with it. A couple of you may remember the issues I've been having with my 1992 RS. I was driving home from work back in January and the car up and died on me out of nowhere. I had it towed home, and it hasn't started since (except for one time it ran briefly and poorly).
The root problem here is no spark from the coil. Injectors are not firing as a result of no spark condition.
Here's what I've done to the car and the order in which I did it:

1) Checked codes, got 12, 13, 15. None are related to my problem.
2) replaced pickup coil.
3) swapped on a "known good" spark module (the one under the cap).
4) replaced coil.
5) replaced ECM
6) replaced distributor with remanned unit
7) Checked all wiring from ECM to every sensor, module, injector, etc. with Multi-meter and visually. Found no faults.
8) tests on pickup coil, ignition coil, and two different spark modules all come up good.
9) all system grounds verified good, with multi meter and visual inspections
10) I cleaned the coil mounting brackets with a wire brush to ensure a solid ground

I've checked for spark with the distributor 4-wire connected, disconnected, with the tach lead disconnected, everything. The rotor is turning when I crank the engine. I have 12v at the coil with ignition on, and 42psi at the rail while cranking.
Here's where things get a little more interesting:
The one and only time I've managed to get fire in the last three months was for about 5 minutes a few weeks ago. I had it hooked up via jumper cables to my Duramax (you may know a diesel truck uses two batteries, so plenty of juice). It started, but ran poorly because it was out of time. By the time I went and got my timing light and it got all hooked up, the car wouldn't start again and hasn't since.
The reason I find this interesting is because even though I have 12v at the coil with ignition on, it drops to about 9.5-10.5 while cranking, this was tested last night, only this time the jumper cables were hooked up to my buddy's Mustang (would have had to move it to hook up to the DMax again). Also, back when the car was running, I was noticing an intermittent problem at night. Sometimes the lights (all of them, headlights, dash lights, everything) would dim, and battery gauge would drop well below 12v while stopped at light, or in a drive through or parking lot... anytime the engine was at idle with the headlights on. Placing the car in neutral and raising the engine speed, or driving the car, would alleviate this, and again, the problem was intermittent. The day the car broke down for good, it was a cold, rainy, gloomy day, and I did have my headlights on.
If you're still with me, here's my question: Is 9.5-10.5v at the coil while cranking "good enough", or has my issue been a power problem all along? Or have I apparently overlooked a bad wire/ground somewhere?

Thanks for the help!
(I'm posting this in the Tech/General area as well)

Dave

 

Did you ever find anything out about this. This is VERY similar to the issue I'm having:
https://www.thirdgen.org/forums/elec...ied-again.html



Jeff