So I swapped the PCM with the above mentioned freebie I got from a tuned '94 Z28 M6, same as my car, and it did the SAME EXACT THING.

I discovered a pink wire with a splice connector on it, on one of the harnesses.... for no reason. I got the shop manuals out and discover this pink wire (#30 on red connector I believe) is for the ignition!!!!

Makes sense that this wire w/ splice connector could very well be the culprit. I'm guessing someone used it for a tach signal or something in the past?

Anyway, remove splice while car is running and jiggle. Car stops.

Could be just a coincidence.

Cut/strip, butt connector, heat gun, problem solved, right?


No. Car starts and still shuts off intermittently.


Curious about battery cables I add an extra ground from the battery to the ground studd on passenger wheel well. No change.

Pull under-hood fuse panel apart to investigate - there's a 10A IGN fuse in there, wondering if the wiring to it may be bad. Start car, jiggle all that, inspect thoroughly, nothing. Car still intermittent.



Button it all back up, put everything away, start car and it runs for 45 minutes w/o issue.



I'm wanting to chase this #30 wire, so I look in the shop manuals and it says it's tied into the MAF, COIL, and something else. I'm really thinking it could be the culprit.

Am I on the right track or is this sounding more and more like I need to do the Opti diagnosis?

 

The pink wire is a power wire that is a common power wire in the harness, it connects to the harness on the passenger fender, get a ohm meter and start testing wires man.

 

It's circuit #439 wire if I'm not mistaken.

Shop manual shows it powering a few different things, one of which is the fuel pump relay... which I didn't find yet but I'm assuming it's in the car somewhere.

 

Fuel pump relay is behind left front kick panel. You can feel it click sometimes upon key-on if your foot is on the dead pedal.

 

I know you said the icm is new. What brand is it? I have had problems with cheap aftermarket brands. Some parts stores (O'Reilly's if there's one in your area) can bench test them. I've run into a number of them that were fine until you tried to accelerate into upper rpms (over 3k).

 

ICM was bought from RockAuto as a Delphi unit if I'm not mistaken. I have receipts - I know I bought the best and/or OEM as I didn't want to take any chances.

Left front kick panel - I'm going to pull that whole assembly out and inspect all the wiring going to it and the connectors.

This damn thing...

 

I had the same issue. Car would run perfect but just die whenever it wanted. Put a delco icm and spaced it off he head and never had another issue

I had an opti do the same thing as well. Would die and as soon as I'd coast to a stop it would fire up. No codes for the longest time and eventually it started throwing codes

 

Guess I'll take the ICM down to Advance Auto and have them scan it. Can't hurt (unless they fry it?) and only takes a minute to pop it off.

 

Do you know where the moisture got in at? Look over your PCM connectors as well, I had a connector corrode and looked fine until you started moving things around, wire came right out without the end!

 

The connectors and all the pins look good and secure. I've cleaned them with contact cleaner and tugged at each and every wire. I wish a wire would just pop out! lol

Best guess on the moisture was the rubber seal between the two PCM cases failed in some way due to being open in the past for PCM tuning. I can't blame anyone, as I said in the OP, car ran awesome for 3 years, sat for another 3, and has been having intermittent issues since getting it out of storage.



I had 15 or so mouse traps in the barn with the car as well as put it up on jackstands w/ the wheels off so any mice that could've run the course of traps and somehow climbed up slippery jackstands to make it in would've also probably been deterred by the ultrasonic mouse deterrants (noise things) I had plugged in out there. I did my best to prevent the "mouse ate all my wiring" situation and I think I succeeded. I don't think that is a concern, it was worth mentioning though.