Sporadically running rough+misfires on track

[thegenius46m]

Is the car worse in vacuum than at wot? These cars usually are in my experience. Does unplugging the maf help the idle and stop the misfiring? Car would run rich to comp for unmetered air. How old are your injectors?

[CrookedCommie]

I had a really strange misfire on track issue recently. Only happened on left turns. Turns out my intake boot was not fully seated on the airbox and left turns ever so slightly pulled it away and opened a gap sucking in massive amounts of unmetered air causing the ecu to violently cut fuel. It was like the engine was coughing and misfiring. Tightening the clamp fixed all.

This sounds similar to what I experienced. I will go through and check the airbox - I was in there two weekends ago replacing a throttle actuator and it may have taken a weekend to open something up for unmetered air. Thanks C!

[foolio]

I had a really strange misfire on track issue recently. Only happened on left turns. Turns out my intake boot was not fully seated on the airbox and left turns ever so slightly pulled it away and opened a gap sucking in massive amounts of unmetered air causing the ecu to violently cut fuel. It was like the engine was coughing and misfiring. Tightening the clamp fixed all.

[CrookedCommie]

Hi everyone, I have the following weird issue at VIR over the weekend. Hoping to get some pointers/tips on what to look for.

While on track into a session, the engine would start to run low on power and rough for a couple turns, then everything went back to normal after about 30 seconds- back to full power. Running codes would give me cylinder misfire 1,2,3,4,6 codes as well as the multiple cylinder misfire code. Only other error code was for EGT sensor - which was replaced with a brand new one on Saturday. I replaced the 6 coils with new Duralast ones, but did not change anything. I found the vacuum line at the back of the fuel rail was unplugged, so got that fixed, ran two full sessions with no issues, but then ran into the same problem on the next session. I checked grounds, did not seem like any were disconnected. The fuel system is pretty much new except for the fuel pressure regulator. The car ran with no engine issues the previous weekend.

So far I have the following to check:
Check vacuum lines and airbox
Replace fuel pressure regulator, double check fuel pressure
Put in 6 new Bosch coils and spark plugs (4-5 seasons old)
Check wiring and grounds in engine bay, fuse panels, etc.
Maybe not a bad idea to replace all the O2 sensors? They are about 4-5 seasons old.

Any other suggestions or tips are really appreciated. This one may be hard to diagnose, as I'm not sure how to recreate it. It would happen 20 min into a session, 10 min, sometimes as soon I went out. After each time I pitted as I did not want to keep running the car and turning into a rolling chicane.

-Rudy