Another high RPM misfire

kulixo

New Member
May 26, 2020
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Hi!

I've probably read 20+ threads regarding this topic, without finding a solution to my problem.
Misfire at 6000rpm+, mostly in 3rd or 4th gear when starting pull from below 4000rpm.
9/10 times cylinder 5.
HPFP mostly stays above 2000psi, but when it misfires it sometimes dives to like 1500psi for a brief second. But I don't know if it's a consequence of the engine shutting the cylinder and switching fuel mode.

Some of the things I tested:

  • 1 step colder plugs (0.0018")
  • PR coils
  • Index 12 injectors (also made sure they seal properly)
  • Turned of misfire detection above 6000rpm
  • MSD81
It seems to misfire regardless of boost level / timing, I get misfires at both 28psi and 20psi.
What I've noticed though is that it seems to be happier if I run it a little leaner than I want to.
12.5 AFR seems to work better, while 12 AFR would misfire every pull.

I can rule out any internal engine damage, I've replaced piston rings, cleaned valves etc and took the time to make sure that everything is alright.
I also tried running with another engine block/head, and still got the issue.

The car is AT with hybrid twins, PI on 100% E85.

Log with misfire: https://datazap.me/u/kulixo/missfire?log=0&data=21

Any suggestions? I feel like I've tried most of the common stuff.
Maybe O2-sensors, but they don't throw any codes.
 
Last edited:

kulixo

New Member
May 26, 2020
6
0
0
An update if anyone with the same problem finds this thread.
I replaces 02-sensors, which didn't help.
I then replaced bank 2 injectors (again), and have now done 50+ pulls without issues. Seems like one of my new index 12s must have been bad from factory.