'92 with Ignition Problems?
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 763
Likes: 42
From: Detroit MI
St. Jude Donor '05-'06-'07-'08-'09-'10
'92 with Ignition Problems?
Hey everyone and greetings from the C3 forum.
I have a friend with a '92 and he is having problems. His description is below.
"Mine has been acting very strange lately, sometimes stumbling, missing and cutting out and then running as if nothing was wrong again. The trouble codes recently have been 16, 27 and 36 which according to my service manual are ECM and distributor related. While idling the other day, I 'thumped' the top of the ECM with my fist and it quit! Should I just replace it? I have spoken to general repair shops but they don't give me a 'warm & fuzzy'"
Is this the dreaded Opti-Spark?
Also, can anyone recommend a repair shop in the Detroit area who won't screw him?
Thanks
Tom
I have a friend with a '92 and he is having problems. His description is below.
"Mine has been acting very strange lately, sometimes stumbling, missing and cutting out and then running as if nothing was wrong again. The trouble codes recently have been 16, 27 and 36 which according to my service manual are ECM and distributor related. While idling the other day, I 'thumped' the top of the ECM with my fist and it quit! Should I just replace it? I have spoken to general repair shops but they don't give me a 'warm & fuzzy'"
Is this the dreaded Opti-Spark?
Also, can anyone recommend a repair shop in the Detroit area who won't screw him?
Thanks
Tom
Burning Brakes
Joined: Oct 2004
Posts: 1,094
Likes: 0
From: West Palm Beach Florida
Try this... there is a post in here that states there could be a corrosion prob with the ECM connector.
http://forums.corvetteforum.com/showthread.php?t=942794
Quote from a member:
Check the wiring harness connector from the ECM to the Opti. Several guys have had corrosion on the prongs in the connector, and it caused flaky ignition behavior.
3 hp gain from the MAF screen? Isn't the margin of measurement error on a dyno like 3-5 hp anyway?
http://forums.corvetteforum.com/showthread.php?t=942794
Quote from a member:
Check the wiring harness connector from the ECM to the Opti. Several guys have had corrosion on the prongs in the connector, and it caused flaky ignition behavior.
3 hp gain from the MAF screen? Isn't the margin of measurement error on a dyno like 3-5 hp anyway?
7th Gear
Joined: Oct 2004
Posts: 7
Likes: 0
Still stumped
I finally found the connector to the distributor, (upper, passenger side) removed it and found it to look 'as new'. I then managed to remove the coil wire and did a resistance test which was the same as the replacement wire on my Chevy pick-up. I guess this means I need to take it somewhere to have it analized by a pro........
Burning Brakes
Joined: Jun 2003
Posts: 827
Likes: 1
From: Henderson NV
The above is good advice but I'd like to throw something out on the table. If the symptoms include rough idle and surging, it might pay dividends to check out the TPS (Throttle positioning sensor.) It's not the most robust component on these models and can cause a lot of false codes to pop up. The DTC code signaling sensor failure is usually 21 or 22. But check out the electrical connection if these codes aren't being sent. When I had my 92, I about went nuts trying to track down the cause of wierd idle, stumbling, etc. and it was right in front of me. Someone had squirted lubricant on the TPS at one time and It mucked up the works. I sprayed electronic cleaner on and around and into the connectors. End of problem. BTW, I wasn't getting a sensor failure code, either. The TPS is just a resistor, similar to a volume control and can get dirty. Just a thought.
7th Gear
Joined: Oct 2004
Posts: 7
Likes: 0
Maybe if weather was warmer here......
Thanks RedC4, mine is too (49k/ZF6 cpe.). Is that Lahaina as in Maui? Must be nice. We were there in Dec.,'98, did some whale watching out of the marina there. I remember a huge Banyon tree nearby....
The problem I'm having is intermittent, may have been having it a long time and will try anything to get her consistant. I drove it in Sept. after leaving it sit since last november. It starts immediately, everytime. It drove perfectly for 3 weeks when for some reason I lugged the engine in 2nd or 3rd and then began cutting out and all. After parking a few weeks, it drove great again, strong & high RPM but I couldn't trust it so I sat idling a few moments when it started to shake and run iratically. I watched the gauges to see anything and before it died, the tach was bouncing from 600 to 6000 like crazy. I backed it out of the garage the other day to turn it around and at low RPM it sounded like it wanted to start shaking again. Any ideas?
The problem I'm having is intermittent, may have been having it a long time and will try anything to get her consistant. I drove it in Sept. after leaving it sit since last november. It starts immediately, everytime. It drove perfectly for 3 weeks when for some reason I lugged the engine in 2nd or 3rd and then began cutting out and all. After parking a few weeks, it drove great again, strong & high RPM but I couldn't trust it so I sat idling a few moments when it started to shake and run iratically. I watched the gauges to see anything and before it died, the tach was bouncing from 600 to 6000 like crazy. I backed it out of the garage the other day to turn it around and at low RPM it sounded like it wanted to start shaking again. Any ideas?
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Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
it's sitting too much. too much rest will allow moisture to build up in the cap, which will cause poor drivability.
Carbon tracing is a bitch!
The tach bounce is causes by a bad tach filter. I assume yours is an LT1? If so, your opti is probably dying.
Carbon tracing is a bitch!
The tach bounce is causes by a bad tach filter. I assume yours is an LT1? If so, your opti is probably dying.
7th Gear
Joined: Oct 2004
Posts: 7
Likes: 0
The car sits too much because it's Michigan! Weather forecasts last spring and summer seemed to have daily rain until September. Now it gets put away again but I wish I could fix it first. Should this problem be moved to the technical column?
