93 Sometimes missing when driving
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3rd Gear
Joined: Sep 2006
Posts: 3
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93 Sometimes missing when driving
I have a 93 corvette with about 155,00 miles on it. I have replaced the spark plugs, wires within the last year or so, and optispark last week. Some days the car runs perfect and every other day when driving she feels like she is running on 6 cyclinders with no power. I am not getting a service engine soon light. Could it be something else that is electrical and is so wouldn't it be running bad all the time. On days she is running good, I run it for about 30 min and give the car time to get to normal temps, so the O2 sensor should be working okay. Does anyone have any suggestions.
Race Director
Joined: Sep 2001
Posts: 14,622
Likes: 748
From: NEwhere Ohio
I have a 93 corvette with about 155,00 miles on it. I have replaced the spark plugs, wires within the last year or so, and optispark last week. Some days the car runs perfect and every other day when driving she feels like she is running on 6 cyclinders with no power. I am not getting a service engine soon light. Could it be something else that is electrical and is so wouldn't it be running bad all the time. On days she is running good, I run it for about 30 min and give the car time to get to normal temps, so the O2 sensor should be working okay. Does anyone have any suggestions.
Also, might want to recheck that your spark plug wires 'clicked' onto each plug. I ran into this problem where it ran like crap and it turns out the spark plug wire to the first cylinder on the left side was loose.
since you havent mentioned the following items, Id suggest looking at these as well:
fuel filter
ignition coil
and put a scantool onto your diagnostic port to see if any codes are being thrown.
good luck.
Racer
Joined: Oct 2008
Posts: 299
Likes: 1
From: Ottawa Ontario
Why does letting it get up to temp indicate the o2 sensor is working ok? I thought that they weren't in the loop when the engine was cold and were engaged when everything is up to temp?
My first thought after reading your post was a bad o2 sensor. Can you hook up a laptop to your car? If you can then you can watch the readings on the o2 sensors. That's how I identified mine was bad (and which one) before replacing it. Mine intermittently threw the SES light though.
My first thought after reading your post was a bad o2 sensor. Can you hook up a laptop to your car? If you can then you can watch the readings on the o2 sensors. That's how I identified mine was bad (and which one) before replacing it. Mine intermittently threw the SES light though.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
sounds like the coolant temp sensor is faulty, and the ECM does not know if the engine is cold or hot intermittantly. This sensor is different than the temp gauge sensor. Also look for loose wires, chafed wires, bad grounds, restricted fuel filter, and put a fuel pressure gauge on it to determine that the fuel pump is still putting out it's required pressure and the regulator isn't bypassing too much fuel.
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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I know you replaced the wires recently, but open the hood at night or in a darkened garrage, pull the hood lamp fuse, then start the engine. Look for electrical creepy-crawlies, sparks, or other gremlins arcing along the plug and coil wires.
These HEI equipped cars are really sensitive to bad wire(s).
These HEI equipped cars are really sensitive to bad wire(s).
