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

Spark plug check #7 strange

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Old Aug 29, 2018 | 12:12 PM
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Default Spark plug check #7 strange


Hi after getting back on track after the loose torgue converter I changed my week old plugs and found ou that number 7 had nothin goin on.
All others look like the plug on the left.
I now checked for spark, plug boot on, pulsation at the old style injector(going to check it out), is there anything else that will affect #7 except the distributor cap?
Thx for any ideas.

Last edited by xrav22; Aug 29, 2018 at 12:52 PM.
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Old Aug 29, 2018 | 01:09 PM
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….. Lack of compression …..
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Old Aug 29, 2018 | 01:17 PM
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Are you losing any coolant?
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Old Aug 29, 2018 | 01:19 PM
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Is the plug good?
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Old Aug 29, 2018 | 01:22 PM
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No coolant loss, assuming plug is good it was brand new. Just put NGK GPower in and it seems much better but I have only made my fixit video, I will finish checking things
after the test drive. I also added Lucas fuel injector cleaner for now.
THX

Last edited by xrav22; Aug 29, 2018 at 01:23 PM.
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Old Aug 29, 2018 | 01:34 PM
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The plug on the right looks like it's firing and burning cleanly. The insulator is not white but colored so it is working. If it was not firing, it would be wet with fuel. The plug on the left to me doesn't look like it's burning the way it should after only 1 week. It looks almost fouled.

Last edited by 383vett; Aug 29, 2018 at 05:52 PM.
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Old Aug 29, 2018 | 07:44 PM
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..... If the car sat for a long time , you might try tapping on the injectors … I use a wooden paint stirring stick and tap with the handle of a good sized screw driver … wouldn't hurt to hit them all …..
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Old Aug 30, 2018 | 08:28 AM
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Originally Posted by 383vett
The plug on the right looks like it's firing and burning cleanly. The insulator is not white but colored so it is working. If it was not firing, it would be wet with fuel. The plug on the left to me doesn't look like it's burning the way it should after only 1 week. It looks almost fouled.
^^^ This ^^^
Track cars need NGK's or Autolite plugs.
If using corn gas suggest Strar Tron fuel additive.
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Old Aug 30, 2018 | 09:12 AM
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….. I disagree … there's NO color at all on the plug to the right and according to the first post ALL of the other plugs look like the left one … the right plug is firing/getting spark , I can see a line on the center electrode approx. 1/16th inch up from the end … but there is no color or mark on the ground strap … there should be a heat range mark at least somewhere between the tip and the plug body … that plug shows no evidence of combustion in the #7 cylinder … easy enough to check with a laser infrared thermometer about $50 bucks at Harbor Freight … or do the water drip or spray on the exhaust manifold … cold enough , like that one looks to just be able to touch the exhaust manifold or header …..
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Old Aug 30, 2018 | 09:15 AM
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….. I DO agree however , that Champion plugs would be my last choice … like last plugs on earth choice …..
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Old Aug 31, 2018 | 01:13 PM
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Fixed , started to follow the tips today and noticed my injector plug had come up and was not firing the injector. It looked like it was on, and felt like it too.
I see the heat burning off the #7 now and idle does not surge anymore
Thx of course for the tips.
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Old Aug 31, 2018 | 10:19 PM
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Originally Posted by xrav22
Fixed , started to follow the tips today and noticed my injector plug had come up and was not firing the injector. It looked like it was on, and felt like it too.
I see the heat burning off the #7 now and idle does not surge anymore
Thx of course for the tips.
its allways the simple stuff
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Old Sep 1, 2018 | 07:08 AM
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Originally Posted by C409
….. Lack of compression …..
sounds right. Head gasket time.
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Old Sep 1, 2018 | 07:59 AM
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Originally Posted by kenmohr
sounds right. Head gasket time.
Go back 2 posts... he said he fixed it.
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Old Sep 1, 2018 | 10:14 AM
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Originally Posted by 81c3
Go back 2 posts... he said he fixed it.
Sorry missed post. Good news.
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