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-   -   Cold start misfires & Timing Corrections (LPFP?) (https://www.n54tech.com/forums/showthread.php?t=63000)

Msoden82 08-14-2020 07:32 AM

Cold start misfires & Timing Corrections (LPFP?)
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Hi everyone,

Iíve been having a cold start issue for a few months now that is frustrating. Every morning after the car sits 8+ hours I have consistent misfires and the car starts to shake. I also get sputters and pops out the exhaust.

Misfires have been consistently on cylinders 4,5 & 6. Occasionally 2 and 3.

Mods are: MHD stage 1+ V7, DCI, and FMIC running 93 octane.

So far installed: new Delphi coils, new NGK step colder plugs at 0.022Ē, new Index 12 Injectors programmed to car, walnut blast, cleaned vanos solenoids, and checked O2 sensor voltages via Autel MX808 scanner.

Still having misfires every morning with occasional engine lights. Also have 3rd gear WOT log with timing corrections consistent on most cylinders.

Build date on car is 03/2009 so Iím MSD81. Only thing I can think of is maybe the LPFP sensor is going out? LPFP is starting to drop pressure so I know Iíll need a new one at some point.


Thanks for any and all help. At wits end here.

mojo20032004 08-15-2020 04:49 AM

Check gap on the plugs and make sure they are in fact the gap.

Msoden82 08-15-2020 08:38 AM


Originally Posted by mojo20032004 (Post )
Check gap on the plugs and make sure they are in fact the gap.

I checked and they are gapped correctly. These are also my second set of plugs gapped at 0.022Ē because the first ones had oil on them from the VC leaking oil into the spark plug tubes.

Msoden82 08-19-2020 01:33 PM

Trying to update this thread for people who may have similar issues as me so that it is documented. After running a cold start log, I’ve found that my STFT in bank 2 skyrockets and is sporadic throughout the cold start (+2 to +30 for valued). I also have bank 2 AFR hovering around 15-17.5 while bank 1 is consistently around 14.5. I believe the DME is trying to compensate a lean condition by adding fuel.

I will be checking for a vacuum leak in the next day or two. Will be checking vacuum lines (which were just replaced) as well as pcv, throttle body, and intake manifold. Had the car recently walnut blasted so there is a possibility the mechanic did not bolt the manifold up perfectly or forgot to reinstall the line to my RB external pcv system on the TB.

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