92 running very rough
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Intermediate
Joined: Jun 2006
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92 running very rough
I have a ’92 Corvette with 63k miles. It started running rough so I checked for codes. I showed that it was running lean and needed a RH O2 sensor. I replaced the o2 and reset the codes. I also replaced the gas filter and checked for pressure at the Schraeder valve. It still ran rough so I checked for spark at each plug with a spark tester and replaced the plugs. The Bosch platinum + 4 plugs (10k miles on them) that I took out looked carboned up and oily. The car does not use oil. It still runs very rough—like it is only running on 6 cylinders. It is not showing any codes. What next?
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From: Canton GA
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St. Jude Donor '03-'05-'06-'10-'11-'12
Take the Bosch plugs out and replace them with the cheap AC Delco ones. I had a '92 that didn't like the fancy plugs AT ALL!
Check all of your plug wires. Make sure they aren't arcing against the engine parts. Get the garage real dark, start the car and visually trace the wires from the Opti to the plug, watch for any stray sparks. I've seen that on more than one 'Vette.
Check all of your plug wires. Make sure they aren't arcing against the engine parts. Get the garage real dark, start the car and visually trace the wires from the Opti to the plug, watch for any stray sparks. I've seen that on more than one 'Vette.
Team Owner
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From: Fort Knox, KY
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Use the NGK TR-55 Platinum Plugs after you've replaced your plug wires and looms.
Also, I like to replace 02 sensors in pairs, since they gradually lose their sensing parameters as they age.
You should also clean your TB and IAC pintle, too. You'd be surprised at all the carbon and resin that gets trapped in their over time. It's part of my annual maintenance regimen, now.
Also, I like to replace 02 sensors in pairs, since they gradually lose their sensing parameters as they age.
You should also clean your TB and IAC pintle, too. You'd be surprised at all the carbon and resin that gets trapped in their over time. It's part of my annual maintenance regimen, now.
Burning Brakes
Joined: Nov 2005
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From: 1992 LT1 6 speed Cayman Islands
Originally Posted by Jerry9202
I have a ’92 Corvette with 63k miles. It started running rough so I checked for codes. I showed that it was running lean and needed a RH O2 sensor. I replaced the o2 and reset the codes. I also replaced the gas filter and checked for pressure at the Schraeder valve. It still ran rough so I checked for spark at each plug with a spark tester and replaced the plugs. The Bosch platinum + 4 plugs (10k miles on them) that I took out looked carboned up and oily. The car does not use oil. It still runs very rough—like it is only running on 6 cylinders. It is not showing any codes. What next?
Try cleaning your IAC valve and see if that helps or you may have a leaking injector.
Try to pull the codes again and see what the computer is telling you with the new O2 sensor. If it is the same you may have a bad connection to tghe O2 sensor.
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From: Canton GA
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St. Jude Donor '03-'05-'06-'10-'11-'12
Does it run rough as soon as you start it (engine cold)? If so, it's not using the O2 sensors until closed loop, it would rule them out for now.
Another trick you can use is to pull the spark plug wires off one at a time to see if it makes a difference. If you pull one off and the engine runs rougher, that cylinder is probably OK. If you pull one off and it doesn't make any difference at all, that cylinder is suspect (spark or fuel).
One last thing: Check the coil wires! Several people have had the coil wire arc against the bracket on the way down to the opti.
Which brings up one more culprit - the Opti Spark Distributer. It's possible that it has some carbon tracing. It may not set a code but you'd get erattic engine behavior. Good luck!
Another trick you can use is to pull the spark plug wires off one at a time to see if it makes a difference. If you pull one off and the engine runs rougher, that cylinder is probably OK. If you pull one off and it doesn't make any difference at all, that cylinder is suspect (spark or fuel).
One last thing: Check the coil wires! Several people have had the coil wire arc against the bracket on the way down to the opti.
Which brings up one more culprit - the Opti Spark Distributer. It's possible that it has some carbon tracing. It may not set a code but you'd get erattic engine behavior. Good luck!
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Le Mans Master
Joined: Feb 2006
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From: Louisiana
Originally Posted by ShawnZR-1
Another trick you can use is to pull the spark plug wires off one at a time to see if it makes a difference. If you pull one off and the engine runs rougher, that cylinder is probably OK. If you pull one off and it doesn't make any difference at all, that cylinder is suspect (spark or fuel).
