Misfires at WOT
 

Getting misfires at WOT......P0300 and cylinders on both sides. I wonder if this is due to my air intake setup, I added a 3" silicone intake with KN filters, Pressure sensors not hooked up....thoughts?


engine runs fine and no codes after they are cleared

Put the stock airboxes back in....no more issues...you need those pressure sensors

This sounds like a similar story:

https://mbworld.org/forums/m275-v12-...ml#post7225313

He came to the same conclusion.

Did you get misfires straight away, or did they take some time to appear?

Nick

Took time and progressively worse

It would over rev and boost quickly, not good....stock airboxes and no issues, posted a fix on his string

So I am now getting misfires typically it was only when the car was just getting warmed up, today it happened about 20 minutes of driving, I usually get a P0300, and random cylinders..... 7 8 10 today; but 3, 5 a few drives ago so its not exclusive to one side.

Hard to pin down at this time, would it be worth disconnecting the battery and resetting everything....and which battery do I disconnect?

Misfires are seeming to occur only when tipping into the throttle from a roll, part throttle....45-50...then hard throttle or tip in ...

P0300
FLsys1 CL
FLsys2 CL
Load % 42.4%
ECT 208
ShrtFT1 -1.6
LngFT1 4.7
ShrtFT2 0.0
LngFT2 5.5
MAP KPA 105
RPM 2375
VSS(KM.h) 108
Spark -21
IAT 54 C
TP% 28.6%
Air_stat Off

Took the tune off, issue is not presenting now....might be the tune

Well after about 100 miles of trouble free driving, Check engine came on with stock tune....didn't notice it until after the CE appeared. So its not the tune, the tune just makes it worse. going to change the fuel filter and see if it helps

Well I changed the plugs when I first got the car.....pre-gap plugs. .031, I pulled them regapped to .024 and then took it out and no misfires with tune. I have had false hope with the car before on these issues, so lets give it a few days before I claim victory

No Misfires with tune.....idle is much smoother

Good news, what plugs?

NGK Iridium Ix Spark Plug (BKR6EIX)

Why those over the IFR6Q-G/?

Probably had a lot to do with trying to find 24 of the same plug and b)works for car and good reviews for application

Fair enough, if they are gapped the same they are the same apart from slightly shorter longevity. Same heat range etc.