Electrical Mayhem!

[RMiller]

This is a really difficult problem to solve, as it turns out, so I'll appreciate any good advice you guys can give me.

Symptoms: Car shuts off seemingly at random. Different temps, different weather, while idling, right after boosting, etc. Injectors click wildly just with the ignition in "on" position w/ the fuel pump on. Sometimes the fuel pump goes on/off sporadically at the same time and I can hear the relay, along with the a/c relay clicking and engaging/disengaging the a/c clutch. Sometimes it starts up normally, sometimes it doesn't.

What I know: I have spark in all cylinders. My wiring is correct, I just broke it all down to check. My relocated battery to trunk is my skapegoat for some reason. I have 2 different ecu's w/ same result. If I unplug the CAS the injectors still go haywire. It seems like electrical interference or electrical surging or something causes a malfunction. Like I said, this stuff happens randomly. If I turn the ignition off, then on, it may stop going crazy. However, even if it's not going crazy and I remove the CAS and turn it the injectors do not open. This is when the car becomes retarded, not when it's my baby.

What's crossed my mind:

Bad relay-nope, multiple relays do itBad CAS-nope, stuff goes crazy w/ it unpluggedI blew a couple fuses a while back by my ghetto KAE alternator grounding against my oil filter. I'm worried about wire shorts, but that would surprise me if that's the case.Interior electrical stuff works perfectly fine regardless of the engine's stubborness and always has, so it seems like my battery ground and power wire are kosher.Wiring-doubt it, I went over it several times, plus the car shuts off and goes wacko without me touching anything.

Summary: electrical issues cause relays to go nuts, power inconsistant to a/c, fuel pump, and injectors receive signal to open without CAS moving. I feel like I've covered all the bases, but I know I'm missing something.

[RMiller]

Still stumped. If you have ideas please DON"T HESITATE TO ANSWER!

[WeldingHank]

i kind of had a similar problem. it was all traced back to a bad ground. ground you battery and ground the rest of your engine ANYWAY you can. my car just shut off once while pulling into my driveway, went into the trunk and wiggled the ground strap and it came back on. try that 1st.

[float_6969]

I'm with Hank. This sounds like a grounding problem to me too...

[RMiller]

Alright, I will check that. I always suspected the battery ground in the trunk. I have it bolted to the base of the trunk, there may not be enough contact.

I worked on the problem today. If I remove the eprom chip from the ecu the pump runs as it is supposed to and I don't hear injectors opening up. However, the injectors must just stay open because I start to smell fuel like a mother. Part of me thinks the chip may not have made a good enough connection on all the pins, but it's hard to tell. The CAS won't fire injectors when rotated, so that's the issue. Interesting: I would crank it over a few times, then I'd turn the key and it wouldn't crank. I thought that was kind of weird. But after a few seconds it would crank again. I had spark when I checked, but then it started, so I assume I don't have spark or fuel when it acts up.

I have my money on the battery ground in the trunk, I need to get that crap sorted.

[r34 gtr]

yeah, i couldnt get my car to start and people suggested i put some more grounds on it. i got some 4 gauge battery wire (from advance, 18in with the eyes on both ends) and ran one from the firewall to the intake manifold, from the intake manifold to the battery tray, and from the left strut tower to the head (where that little bracket is right above the exhaust manifold at the front of the engine). car fired instantly, but it didnt run for other reasons. i suggest heavy grounding of the engine. also, check the grounds and 12v pins on the ecu for continuity. if one wasnt working at a certain time it could cause problems. some 12v wires only have current at certain times/ign positions so make sure they all work correctly. you should be able to find all the pins you need at the impactblue ca18 site or here, http://www.users.bigpond.com/w...s.htm

- tim

[float_6969]

Tim, you're so Ghey... Hehehe