Rough Idle when engine is hot, SOLVED
Thread Starter
Instructor
Joined: Sep 2011
Posts: 131
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From: Illinois
Rough Idle when engine is hot, SOLVED
So I was working on the vette again cause the rough idle when hot came back. To explain exactly what was happening, intermittantly when the motor had a load on it the idle would get rough and it sounded like a cylinder was shutting down for short periods. Usually when I work on the car I have tons of lights on so I can see better. Well i was over at a freiends house tonight and we didnt have much light and it started to do it again. I suddendly saw a light but wasn't sure so was shut the rest of the lights of an kept stairing at the motor and sure enough we saw it. A spark plug was arcing through a plug boot right to the heads. There was a micro scopic hole in the boot. So i just happened to have some industrial glyptall paint on hand. So we through some on the boot and reinstalled it. The car idled so rock solid that the numbers weren't changing even a digit. The spark plug has some white pitting corrision on the bolt section on it so tomorrow ill replace that spark plug but the glyptall paint on the boot solved the problem. After months of searching just waiting till the sun went down and the lights were off solved my problem. Has anyone heard of this before?
Team Owner
Joined: Jan 2003
Posts: 20,306
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From: Summerland B.C. Canada
Seen that happen many times. When I don't see it and I feel that it may be the problem, I use my grounded test light and drag the probe across the wires and boots. The spark now has an easier route to ground and you can see and hear the miss, without getting shocked. 
Team Owner
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From: Summerland B.C. Canada
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From: Corvettes ruined my life. CA
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Le Mans Master
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From: Hellinois
Finalist 2020 C4 of the Year - Modified
Back in my drag racing days I learned not to grab a Vertex Magneto by the cap when sweating. If you have never worked with a magneto, one small twist of your wrist will send a blue spark across a one inch gap with ease so you can imagine what it felt like at idle speed. That's why they make those plastic covers for them.
Team Owner
Joined: Feb 2006
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From: San Antonio Texas
Had the "rough idle blues" once on my old Mustang after doing a full cap, rotor, wires and plug thing. Ran worse......couldn't figure it out untill I opened the hood BEFORE I turned on the light one night! What a light show!
It looked like one of those lightning globes they sell at Spincer Gifts! I had bought a set of cheapy A.Z. wires they were running a special on. Yeah, they were special alright. Special junk! New set of quality wires and fixed everything that had me bugged for a week.
It looked like one of those lightning globes they sell at Spincer Gifts! I had bought a set of cheapy A.Z. wires they were running a special on. Yeah, they were special alright. Special junk! New set of quality wires and fixed everything that had me bugged for a week.
Le Mans Master
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From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
Thread Starter
Instructor
Joined: Sep 2011
Posts: 131
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From: Illinois
NGK Iriduim IX Part Number # 739-UR5IX
Street Fire Plug Wire Set Part Number # 121-5563
Plug Wire Set BOSCH Part # 09679
Spark plugs BOSCH Part # 7975 SUPER PLUS
I'm torn between these two sets there is a 50 dollar price difference between the two. What are your opinions on these and maybe if you have a better alternative suggest it. Thanks.
Street Fire Plug Wire Set Part Number # 121-5563
Plug Wire Set BOSCH Part # 09679
Spark plugs BOSCH Part # 7975 SUPER PLUS
I'm torn between these two sets there is a 50 dollar price difference between the two. What are your opinions on these and maybe if you have a better alternative suggest it. Thanks.
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
Why would you want to put those crap Bosch spark plugs in?????
Use the NGK - I've used the V and G in all my vettes
Also I used Taylor Spiro pro wires.
Use the NGK - I've used the V and G in all my vettes
Also I used Taylor Spiro pro wires.
Thread Starter
Instructor
Joined: Sep 2011
Posts: 131
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From: Illinois
MSD-5563 MSD 5563 Wire Set, Street Fire, 84-91,Corvette,350TPI
NGK-UR5IX NGK UR5IX 14mm Iridium IX Resistor Projected Insulator Spark Plug Tapered Seat Stock# 7177
Ordered and being ground shipped UPS Monday! Here's to hoping that this combo does better.
Anyone know off the top of their head gap size for these plugs to an 85' ?
NGK-UR5IX NGK UR5IX 14mm Iridium IX Resistor Projected Insulator Spark Plug Tapered Seat Stock# 7177
Ordered and being ground shipped UPS Monday! Here's to hoping that this combo does better.
Anyone know off the top of their head gap size for these plugs to an 85' ?
Thread Starter
Instructor
Joined: Sep 2011
Posts: 131
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From: Illinois
