Misfire above 5k
Thread Starter
Racer
Joined: Sep 2015
Posts: 366
Likes: 80
From: Aubrey, TX
Misfire above 5k
2013 427, new heads, new plugs and wires. When I’m running the car hard, Above 5k rpm, check engine light blinks, Car tells me to service traction system. Trying to troubleshoot with the shop, the thought is it has a cat failing, so we’re gonna work on replacing that. Any other ideas that we should maybe look out for in case? Moving to Vegas on Friday so want to make sure the car is buttoned up before we go. Thoughts?
Safety Car
Joined: May 2016
Posts: 4,669
Likes: 1,849
From: Erlanger, Kentucky
I am thinking it's probably a bad ignition coil or coils. I had a similar problem a couple of years ago when I had my 2011 Grand Sport dyno tuned. Above 5K rpm's, it was misfiring on one of the cylinders. Could see it in the diagnostics in HP Tuners and could hear it.
We swapped the suspect coil to another cylinder and the misfire also moved. Replaced the coil and problem solved.
That being said, its not a bad idea to check the plug wires and plugs even if they are new. Sometimes easy to overlook a sparkplug with an improper gap or even damaged porcelain.
We swapped the suspect coil to another cylinder and the misfire also moved. Replaced the coil and problem solved.
That being said, its not a bad idea to check the plug wires and plugs even if they are new. Sometimes easy to overlook a sparkplug with an improper gap or even damaged porcelain.
Burning Brakes
Joined: Oct 2007
Posts: 792
Likes: 195
From: NC
If you aren't getting misfires only on a specific cylinder(s), I'd consider clogged cats. I had this happen after adding a blower with the stock exhaust. After a little while, I was getting random misfires above 5k RPM at WOT and it turned out that the cats were breaking apart.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
2013 427, new heads, new plugs and wires. When I’m running the car hard, Above 5k rpm, check engine light blinks, Car tells me to service traction system. Trying to troubleshoot with the shop, the thought is it has a cat failing, so we’re gonna work on replacing that. Any other ideas that we should maybe look out for in case? Moving to Vegas on Friday so want to make sure the car is buttoned up before we go. Thoughts?
Thread Starter
Racer
Joined: Sep 2015
Posts: 366
Likes: 80
From: Aubrey, TX
So now we’re thinking bad gas possibly? Shop tested and tested yesterday on funk and on street, no issues. Retuned for 91 octane since I’m moving to Vegas tomorrow and 93 isn’t available, no issues.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
I am thinking it's probably a bad ignition coil or coils. I had a similar problem a couple of years ago when I had my 2011 Grand Sport dyno tuned. Above 5K rpm's, it was misfiring on one of the cylinders. Could see it in the diagnostics in HP Tuners and could hear it.
We swapped the suspect coil to another cylinder and the misfire also moved. Replaced the coil and problem solved.
That being said, its not a bad idea to check the plug wires and plugs even if they are new. Sometimes easy to overlook a sparkplug with an improper gap or even damaged porcelain.
We swapped the suspect coil to another cylinder and the misfire also moved. Replaced the coil and problem solved.
That being said, its not a bad idea to check the plug wires and plugs even if they are new. Sometimes easy to overlook a sparkplug with an improper gap or even damaged porcelain.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
You need to first have the car scanned to see which cylinder / cylinders are doing the misfiring. This info will be held in the car's computer memory for a period of time.
Without knowing which cylinder is actually doing the misfiring, your just pissing against the wind trying to figure out what's wrong with the engine.
_________________________
My GS had a bad misfire. The scan on my HP Tuners software indicated it was the #7 cylinder (no other cylinders misfiring) ... come to find out the spark plug wire was almost falling off the #7 spark plug ... pushed it back on securely and no more misfires.
Without knowing which cylinder is actually doing the misfiring, your just pissing against the wind trying to figure out what's wrong with the engine.
_________________________
My GS had a bad misfire. The scan on my HP Tuners software indicated it was the #7 cylinder (no other cylinders misfiring) ... come to find out the spark plug wire was almost falling off the #7 spark plug ... pushed it back on securely and no more misfires.
