03-14-2020, 12:28 PM | #1 |
Drives: 2011 Camaro SS Join Date: Aug 2018
Location: Travelers Rest
Posts: 1
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Need help with misfire after header install it's not the plugs or wires.
I need help tracking down a misfire. Its only on one cylinder under load. Happened after installing longtube headers and cai. I just got back from my tuner and we can't figure out what's the issue. So far I swapped plug wire and coil to another cylinder, ohm tested the injector and swapped the injector to another cylinder. The problem stayed on cylinder #4. The only things I can think of is a broke valve spring, pcm, or a wiring issue. To my knowledge my car has been unmolested before me. I'm about to do a cam swap but need to track down the problem before moving forward.
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03-14-2020, 04:19 PM | #2 |
Drives: 2014 1SS/RS, LS3, NPP Join Date: Feb 2019
Location: Florida
Posts: 184
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On a prior car years ago I had a problem with one plug wire shorting out on the header. It was noticeable in my dark garage at night. Pop your hood and rev the engine in the dark with the help of a friend. Watch around cylinder #4 and see if the plug wire or voltage is doing anything funky. After I discovered it I ran wire separators which fixed my problem. Easy to rule out.
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03-14-2020, 05:01 PM | #3 |
Drives: 2012 SS Vert Join Date: Sep 2013
Location: Austin, TX
Posts: 10
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I had this problem and it was a cracked spark plug. Couldn’t tell just by looking at it but after I swapped it with a new one, it ran great.
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03-15-2020, 09:46 PM | #4 |
Drives: 2011 Camaro 2SS LS3 Whipple Join Date: May 2019
Location: Connecticut
Posts: 1,925
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You say you swapped the wire to another cylinder but didn't say youdid the same for the plug. I would start there. Compression test next.
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03-16-2020, 05:21 AM | #5 |
SomeguyK
Drives: 2010 Black 2SS/RS Join Date: Nov 2014
Location: FL
Posts: 1,947
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Try a new spark plug. Did you remove them when you did the install?
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03-27-2020, 11:42 PM | #6 |
Drives: 2011 2SS, 2006 GMC Sierra Join Date: Jul 2019
Location: MA
Posts: 245
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Any codes?
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03-28-2020, 07:05 AM | #7 |
Drives: 2015 2SS A6 Commemorative Edition Join Date: Nov 2019
Location: Utah
Posts: 433
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I agree with Greenhornet2, compression test next. If that cylinder is low, squirt a bit of oil in it and test it again. If compression gets better with oil, it’s bottom end, if not, it’s top end.
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03-28-2020, 07:25 AM | #8 |
Drives: 2015 2SS A6 Commemorative Edition Join Date: Nov 2019
Location: Utah
Posts: 433
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Black 6.2L SS’s test is good one to try too. When I swapped heads on my 454 and had a miss on startup, shutting off the lights revealed the shorting plug wire
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03-28-2020, 07:55 AM | #9 |
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pull your spark plugs and look at them. you probably cracked one when installing your tubes.
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03-28-2020, 11:04 AM | #10 |
Drives: 73 VETTE ,, 05 2500hd diesel,14 1LE Join Date: Feb 2014
Location: The Left lane PHOENIX AZ
Posts: 2,626
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8 to 5 you have a cracked plug
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