C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old Sep 28, 2016 | 10:24 AM
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Default Dark smoke

Ok ive been hanging out in the background for the last 6 months or so been busy here at work usual things. Im getting a knee replaced end of October so i figured i better use my 93 some before i put her away. She ran good about 20 miles or so. On the trip home i got on her some not to hard and she did fine..until about 4 miles from home. Started running very rough like missing 1 or 2 cylinders? Got her home parked under the car port and about 5 mins went by and out of the left exhaust dark gray smoke. Smelled like un burned gas very strong smell. Smoke lasted for at least 5 minutes. So could it be as simple as a plug wire off? Any ideas out there? Dave
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Old Sep 28, 2016 | 10:52 AM
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Mist the plug wires and look for sparks in the dark. Do not get your opti wet.
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Old Sep 28, 2016 | 11:21 AM
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Originally Posted by antfarmer2
Mist the plug wires and look for sparks in the dark. Do not get your opti wet.
Yeah ill give that a try. Came about very suddenly like flipping a switch.
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Old Sep 28, 2016 | 02:32 PM
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Is it just running rough or is there a mechanical sound associated with the issue like metal on metal or hammering type sounds?

Is the check engine light on or flashing?
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Old Sep 28, 2016 | 02:51 PM
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No sounds just running rough. Bad miss
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Old Sep 28, 2016 | 06:35 PM
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Originally Posted by davewhtt
No sounds just running rough. Bad miss
Check plugs and wires and then give us an update.
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Old Sep 28, 2016 | 06:50 PM
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Plan on doing that this week end. I'll reply back.
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Old Oct 1, 2016 | 08:11 PM
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I don't know if this works or not. If you have a clamp-on timing light, clamp it on each of the plug wires. I'm assuming if a plug isn't firing, you could pick up on it this way.

To check the wires themselves, here's something I've done before. Took a piece of solid strand electrical ground wire and made a J shaped bend in it. I put it in one end of a jumper cable and connected the other end to a good ground. Hooked it around each plug wire one at a time and took it down the length of the wire watching and listening for any arcing to it.

May not be your ultimate problem, but worth a test.
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Old Oct 1, 2016 | 09:06 PM
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This could have just fouled a couple of plugs,I've had this happen after sitting for awhile and then try to run at higher RPM's,but ran fine driving at part throttle.
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Old Oct 2, 2016 | 11:59 AM
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Originally Posted by A Peter C4
This could have just fouled a couple of plugs,I've had this happen after sitting for awhile and then try to run at higher RPM's,but ran fine driving at part throttle.
Checked all wires tried to start her and..god awful noise from I think top of motor ( valve?) Would that have caused this?
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Old Oct 2, 2016 | 04:15 PM
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Originally Posted by davewhtt
Checked all wires tried to start her and..god awful noise from I think top of motor ( valve?) Would that have caused this?
I would not start it again and pull off a valve cover and see if you dropped a valve.
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Old Oct 2, 2016 | 04:30 PM
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Originally Posted by A Peter C4
This could have just fouled a couple of plugs,I've had this happen after sitting for awhile and then try to run at higher RPM's,but ran fine driving at part throttle.
Originally Posted by antfarmer2
I would not start it again and pull off a valve cover and see if you dropped a valve.
That's what I'm planning. Didn't fire I only tapped key. Oh well. Dave
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Old Oct 3, 2016 | 06:57 PM
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Originally Posted by davewhtt
That's what I'm planning. Didn't fire I only tapped key. Oh well. Dave

maybe u have 3 melted wires like i just discovered.
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