Random Misfire at high rpm

Dranthonyrega · 02-12-2023, 07:37 PM

Hey guys

Cant figure this out nor the shop. Track car stock engine.

At only high rpm’s every couple of track days it throws a misfire code. Cylinder 1 or on time multiple. Rrstart the car and it fine.

Coils, plugs and pvc changed and still happens. Car doesn’t hesitate or anything prior to limb mode.

73 K on the motor. Idles smooth and full of power. Never on track fuel. I bring fuel with me and never go out below 3/4 tank.

Yesterday I literally restarted the car while rolling on the track and ran 6 fast laps with no issue after limp
Mode.

Any ideas

Thanks in advance

RhinoComp · 02-13-2023, 11:02 PM

Have you replaced your intercooler? Mine on my 2018 leaked very slowly, like it would take 5-6 months to drain and throw a code for dry charge coolant, but it was still enough to cause what I though was a random misfire after id replaced plugs, coils, whole shebang. My J-pipe even looked dry when I would check to see if there was evidence of coolant. My only hint towards it leaking ever so slightly was that I'd see small air bubbles in the charge coolant expansion tank when the engine was running.

Replaced it with a Mishimoto unit and all issues are resolved. No more small bubbles with the cap off, no more misfires.

It's certainly worth looking into. My leak was so small that I left it filled with water and capped off for a couple of hours and it didn't noticeably leak at all. But if you put a lot of pressure to it (like a high boost situation or pressure test) it can find those leaks and make them more pronounced.

02-12-2023, 07:37 PM	#1
Dranthonyrega New Member 8 Rep 11 Posts Drives: 2015 M4 Join Date: Feb 2023 Location: Danville ca iTrader: (0)	Random Misfire at high rpm Hey guys Cant figure this out nor the shop. Track car stock engine. At only high rpm’s every couple of track days it throws a misfire code. Cylinder 1 or on time multiple. Rrstart the car and it fine. Coils, plugs and pvc changed and still happens. Car doesn’t hesitate or anything prior to limb mode. 73 K on the motor. Idles smooth and full of power. Never on track fuel. I bring fuel with me and never go out below 3/4 tank. Yesterday I literally restarted the car while rolling on the track and ran 6 fast laps with no issue after limp Mode. Any ideas Thanks in advance
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02-13-2023, 11:02 PM	#2
RhinoComp Private 32 Rep 70 Posts Drives: 2019 X5 Join Date: Jan 2022 Location: Issaquah, WA iTrader: (0)	Have you replaced your intercooler? Mine on my 2018 leaked very slowly, like it would take 5-6 months to drain and throw a code for dry charge coolant, but it was still enough to cause what I though was a random misfire after id replaced plugs, coils, whole shebang. My J-pipe even looked dry when I would check to see if there was evidence of coolant. My only hint towards it leaking ever so slightly was that I'd see small air bubbles in the charge coolant expansion tank when the engine was running. Replaced it with a Mishimoto unit and all issues are resolved. No more small bubbles with the cap off, no more misfires. It's certainly worth looking into. My leak was so small that I left it filled with water and capped off for a couple of hours and it didn't noticeably leak at all. But if you put a lot of pressure to it (like a high boost situation or pressure test) it can find those leaks and make them more pronounced.
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