Electrical Nightmare! Please Help...

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Jun 16, 2023 | 12:43 AM

ChuckThornton

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3rd Gear

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Electrical Nightmare! Please Help...

Last weekend I impulse bought a 1992 C4 convertible. I have since had nothing but problems, and I am nearly out of ideas. The car has some sort of issue causing hesitation on acceleration and often it'll run completely fine past 2000 RPM. Trying to get it up to 2,000 RPM is nearly impossible. It jolts, it backfires, etc. I have replaced the spark plug wires the coil wire, and the coil itself. I've replaced the distributor wiring harness, and have had the ICM tested. If the Opti is bad, I don't believe it's the only problem.

I'm now running into an issue of getting the car to start. Sometimes its fine, often it runs for a moment and dies. It may or may not restart immediately. While all of this is happening, the hazards are flashing, but not indicated on the gauge cluster. In situations where the car putters out and won't restart, I have spark. I've tested it multiple times.

I considered myself pretty good with cars, but this one is driving me nuts, and now that my father has passed, I have zero help.

Thanks in advance!

Jun 16, 2023 | 08:29 AM

pedricd

Drifting

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From: Northwest Ohio

Have you checked fuel pressure?

Have you pulled codes?

Jun 16, 2023 | 10:01 AM

Talfryyn

Instructor

Joined: Sep 2022

Posts: 209

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From: Dalbo, Minnesota

Start with the basics. Get the battery and alternator tested. Low or dirty power can cause a host of problems. Check the battery and chassis grounds. Bad grounds gives bad data to the electronics.
check the sensor reference voltages. Multiple engine management sensors share the same reference voltages. If the reference voltage is off the sensor data is wrong.
92’s are known to have connector issues. People disconnecting by pulling on the wires can pull the pins back in the housings giving bad connections when reconnected.
you say you have spark but did you check the base timing? Did you check to see every spark plug wire is going to the correct spark plug?

Jun 16, 2023 | 10:44 AM

dburgjohn

Melting Slicks

Joined: May 2003

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From: Dyersburg TN

this really has an electrical vibe like maybe bad ground wires. Low fuel pressure would likely make it worse the higher the RPM. Big thing is pull the codes and share them here.

Jun 16, 2023 | 02:56 PM

dburgjohn

Melting Slicks

Joined: May 2003

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From: Dyersburg TN

just finished installing a Petris Optispark. Mine ran crappy like you describe and I had code 16. I did not have the oddness on the display and it always started and idled. as I said, codes will tell story. Use the jumper wire or get(borrow) a code reader.

Jun 16, 2023 | 03:01 PM

WVZR-1

Team Owner

Joined: Sep 2003

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A jumper fabricated with the correct mating terminals would be ideal vs stuffing stranded wires as post #5 illustrates.

*** The ALDL is 280 Metri-Pack Female so having some Male M/P 280 terminals for the appropriate gauge wire you're using.

Last edited by WVZR-1; Jun 16, 2023 at 03:09 PM.

Jun 16, 2023 | 11:43 PM

topfuel67

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Joined: Feb 2016

Posts: 1,384

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From: Simi Valley CA

My 92 6 speed convertible had a weird issue I compared to being a turbo Vette. It is mostly factory. It felt like it had good power off the line, but above 3000-3500 rpm it got a boost like a turbo kicking in. I replaced pugs, wires, timing chain, lifters, o2, senors, oil and water sensors, kr sensors etc. I finally got a cord to plug into a laptop and downloaded Tunerpro to datalog it. I found I had 11-14 degrees of knock retard from idle to 3500 rpm. Even at partial acceleration. I ended up buying another chip on this forum that looked like a home burned chip. It solved my issue. I still plan on figuring out how to burn my own chips as this one still doesn't feel like it's dialed in. But it runs pretty good for what it is.
Check out this site for tuning and datalogging. I found plenty of links to get hardware and even free software downloads.
Lt1pcmtuning.com

Jun 17, 2023 | 04:13 PM

ChuckThornton

Thread Starter

3rd Gear

Joined: Jun 2023

Posts: 3

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Quote:

Originally Posted by IHBD

Check Fuel Pressure at the Rail First.

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This is a 1992. It may not be the opti, but it probably is. Here's how to check the codes for an opti problem. You can only do it with the onboard diagnostics, as "reading codes" through the Service Engine Soon light doesn't reveal History codes.

Prepare a jumper wire. Place it in cavities A&G as shown in this pic:

Turn key to RUN. Watch the speedo display. It will begin with C12 in Module 1.0 (the little number next to the big speedo numbers).
Watch all the codes in all the modules, and write them down. If you get lost or want to see them again, turn the key off, then back on and it starts over.

You are looking for H16 in Module 4. H16 is the smoking-gun code for opti problems that are causing drivibility issues.

Clear the ECM Codes. (Module 4):
Install jumper.
Key to RUN
Use TRIP RESET until "4.0" is displayed.
Use TRIP/ODO until "4.7" is displayed. (Note: 4.1 is "display ECM codes". You can 'stop' at 4.1 to see the ECM codes. Then TRIP/ODO to 4.7 to clear them.)
Press and hold ENG/MET until "- - -" is displayed.

Remove jumper. Crank engine. If it doesn't start, good. If it runs, but runs crappy, good.

Recheck for Codes. If H16 is 'back', you can pursue replacing the opti with confidence that it IS the opti.

All that I'm getting is the pass code. I went through the grounds on the bell housing and above oil filter, now the starter won't turn at all. The bell is just going crazy and the flashers randomly turn on and off. It does this with no regularity at all.