Odd start up issue. Not HPFP related.
*Edit* got a engine malfunction warning on start up today when this happened. Code cleared itself before I was able to check what it was...
Let me start by assuring everyone this isn't another misfire/ long crank/HPFP/Injector on start thread..
my car is an 09 E90 335i, FBO/Meth, 46k miles.
Once in a while, I'll get a rough start after hard driving. It's inconsistent and happens maybe 1/15 starts. The car will start up immediately (no long crank and very dissimilar to when my HPFP shit the bed) but exhaust volume will fluctuate significantly. I haven't noticed any fluctuation in RPMs, but it's still a cause for concern. I'm running a vanguard V2, so the sound difference is quite obvious. anyways, the car starts very quiet (almost like it's choking), then seems to 'pick back up' to normal sound.
I remember reading somewhere that it was due to residual meth after shutting the engine off and not to worry about it. but 500 miles ago, my clutch finally started to slip on the dyno, so I went ahead and replaced it with an ACT Street. I had the car on low boost no meth (map 1 JB4 G5 ISO) during break in, and continued experiencing the odd start issue. That being said, I'm beginning to question any residual or left over meth being the cause, since the symptom continued 500+ miles since my last meth use.
Car hasn't thrown any codes, drives completely normally, and there are no visible discrepancies in recent logs. Valves were cleaned 5k miles ago after struggling to isolate constant misfires (ran through plugs/coils/injectors), and haven't had a problem (or misfire) since, though the odd start was present before as well.
Curious if anyone has any ideas, thanks for any input.
Current: 2015 6MT F80 M3
2011 Alpine White DCT E92 M3 FBO
2009 Alpine White 6MT E90 335i FBO + Meth
Last edited by ZTZ1010; 01-31-2013 at 03:56 PM.