Problem stalling, backfiring at WOT high rpm
Thread Starter
5th Gear
Joined: Mar 2018
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Problem stalling, backfiring at WOT high rpm
I recently purchased a c5 that had been sitting for a few months and started to have a problem under hard acceleration and high rpm. I have already replaced the spark plugs/wires. Also on separate occasions i had check engine lights for oil pressure sensor and misfire. I replaced the oil pressure sensor as well as the knock sensor. The misfire was for cylinder 3 so i bought a coil and the problem did not go away. I put a new injector in cylinder 3 and the misfire has seemed to go away, idle is much smoother and the engine seems smoother all around. However, the stalling and backfiring problem is still happening. I am stuck and do not know where to go from here.
Acct Suspended APR 2026 by request
Joined: Dec 2010
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2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
does the car have any mods?... when you changed the plugs what kind did you use and what gap?... what octane gas?... assuming that nothing else is mechanically wrong, a few months sitting isn't very long but if the car spent most of it's life being driven gingerly then it's possible there may be some carbon buildup on the pistons and valves that create problems under heavy acceleration... you might try running a can of seafoam through the intake to burn off any residual carbon then take it out for a spirited drive to blow the excess out
Thread Starter
5th Gear
Joined: Mar 2018
Posts: 5
Likes: 0
does the car have any mods?... when you changed the plugs what kind did you use and what gap?... what octane gas?... assuming that nothing else is mechanically wrong, a few months sitting isn't very long but if the car spent most of it's life being driven gingerly then it's possible there may be some carbon buildup on the pistons and valves that create problems under heavy acceleration... you might try running a can of seafoam through the intake to burn off any residual carbon then take it out for a spirited drive to blow the excess out
Last edited by jbely; Mar 18, 2018 at 07:35 PM.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
No sure you can regap the iridium plugs, don't think it is recommended. I would just get a set of NGK TR5 plugs.
If you hear rattling in the cats, they may be broken up inside and blocking exhaust. Doubtful but possible.
New Era Performance can clean and calibrate your injectors. I had them do a set and they came back great.
Three months is not long, mine sits for six months every year due to weather in the northeast. It is likely something simple.
If you hear rattling in the cats, they may be broken up inside and blocking exhaust. Doubtful but possible.
New Era Performance can clean and calibrate your injectors. I had them do a set and they came back great.
Three months is not long, mine sits for six months every year due to weather in the northeast. It is likely something simple.
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Melting Slicks
Joined: Sep 2008
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From: Espanola New Mexico
You had stated high revs, but did not give a number, so I thought maybe it was the rev limiter. I know that forum members are usually trying to obtain advise and help repairing their cars themselves, but have you thought about taking the car in to a reputable corvette repair shop or tuner shop.
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Change the fuel filter. You can also CLEAN your own injectors. Its easy and can restore their performance if they are just dirty:There is an entire You Tube world on cleaning injectors:
YES, regap the plugs to 0.040
What wires did you install??
Thread Starter
5th Gear
Joined: Mar 2018
Posts: 5
Likes: 0
ABSOFRIGGENLOOTLY! Change the fuel filter. You can also CLEAN your own injectors. Its easy and can restore their performance if they are just dirty:
There is an entire You Tube world on cleaning injectors:
https://www.youtube.com/watch?v=rUUgR94drxg
YES, regap the plugs to 0.040
What wires did you install??
Change the fuel filter. You can also CLEAN your own injectors. Its easy and can restore their performance if they are just dirty:There is an entire You Tube world on cleaning injectors:
https://www.youtube.com/watch?v=rUUgR94drxg
YES, regap the plugs to 0.040
What wires did you install??
Acct Suspended APR 2026 by request
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Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
check the plug gap before you take it somewhere, .020 may not seem like a lot but can make a ton of difference in how the car runs