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Author
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Topic: Normal Spark Plug Wear? (Pic)
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fredfifty
Since
9/2010
Member # 10320
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posted
 
 
I have a SES light on my 99 Tahoe (142k mi) and it reads P0304 misfire cylinder 4. I pulled the plug out (see pic) and to me it looks normally worn, however the gap was about .70 when it should have been .60
I regapped and installed but it still misfires. Im thinking a full tuneup is in order? What do you think.
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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hurting your feelings
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Member # 13641
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posted
Move the spark plug to a different cylinder if mis-fire follows to that cylinder the plug is the problem. An you have a vortec engine an the have a big problem with there fuel injector's an the spider that feeds them.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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fredfifty
Since
9/2010
Member # 10320
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posted
Ive been reading about that spider injection problem...its a 300 dollar part so i hope its not that. So the plug looks normally worn though? I will get or swap spark plugs tmmrw and test it, thanks...
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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hurting your feelings
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Member # 13641
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posted
Looks to be wet in the picture. I would have to see a better picture on the plug.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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fredfifty
Since
9/2010
Member # 10320
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posted
When i pulled the plug out, thats the first thing i looked for, wetness. But it was dry but it had a stale burnt smell if that makes sense.
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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fredfifty
Since
9/2010
Member # 10320
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posted
Better pic i hope
I bought a new ac delco plug, gapped it to .060 per specs and installed in #4 cylinder. Idles better, no obvious misfire when i give it some gas. So i cleared the code, let it run for a couple minutes and no SES light.
I hope that was it...now a full tune up.
[ 2014-11-12, 09:13 PM: Message edited by: fredfifty ]
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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fredfifty
Since
9/2010
Member # 10320
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posted
Dp
[ 2014-11-12, 09:13 PM: Message edited by: fredfifty ]
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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hurting your feelings
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Member # 13641
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posted
Plug does look to be worn.I would give a couple days of drive after replacing that plug just to make sure the mis-fire has gone away.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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Tom Renzo
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Member # 13165
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posted
You did the right thing by replacing the plug and clearing codes to test it. But the gap is a little wide. We run them at .042-.045 max
[ 2014-11-13, 04:13 AM: Message edited by: Tom Renzo ]
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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fredfifty
Since
9/2010
Member # 10320
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posted
What are the pros and cons of .060 and .042? Im just gapping the plugs based off the factory specs, but if it benefits me more to narrow the gap ill do it.
Thanks
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RIP EDSON VELORO
IM A NOOB, EXCUSE ME. THANKS.
92 LX Coupe 5.0 CARB'd BOLT-ONS SMOG LEGAL
62 Rag Impala
Posts: 4953 | Registered: Sep 2010
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hurting your feelings
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Member # 13641
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posted
quote:
Originally posted by fredfifty:
What are the pros and cons of .060 and .042? Im just gapping the plugs based off the factory specs, but if it benefits me more to narrow the gap ill do it.
Thanks
All data says it.060 gap. An that's what I would go by it's a daily driver no need to get crazy with the spark plug gap.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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fredfifty
Since
9/2010
Member # 10320
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posted
I dont drive it much now, but i will when i know the misfire is gone. Curious on the .042 gap though, is it for more power?
Posts: 4953 | Registered: Sep 2010
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hurting your feelings
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Member # 13641
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posted
quote:
Originally posted by fredfifty:
I dont drive it much now, but i will when i know the misfire is gone. Curious on the .042 gap though, is it for more power?
There isn't much benefit to gap the plugs to.042 they may wear out quicker though.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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Tom Renzo
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Member # 13165
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posted
I build many chevy engines in my shop and we have found that a closer gap works much better. Reducing the gap will make it more reliable. As the matter of fact Chevy had a service bulletin on reduced plug gaps. With that the stock gap according to GM is .050-.060 All data says .060 as posted in the vehicles in car emission decal.
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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hurting your feelings
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Member # 13641
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posted
quote:
Originally posted by Tom Renzo:
I build many chevy engines in my shop and we have found that a closer gap works much better. Reducing the gap will make it more reliable. As the matter of fact Chevy had a service bulletin on reduced plug gaps. With that the stock gap according to GM is .050-.060 All data says .060 as posted in the vehicles in car emission decal.
Bone stocker there is no real reason to play with the gap of the plugs.
Posts: 1830 | From: In front of the bank with a 45 an a ski mask | Registered: Jun 2014
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