JB4tech.com - International Turbo Tuning Discussion
KAR KAR is offline
New Member
Posts: 3
Join Date: Nov 2015
Car: 2009 135i
Default Another N54 Cold Start dilemma - 11-30-2021, 11:48 PM

I've been searching for any help at all on my cold start issue across all the various N54-related forums and finally decided I needed to post my own question. So, just to blow through the usual level 1 and level 2 support questions... I've just completed a fairly thorough resto-mod of my '09 135i. I'll leave the pertinent details below. Despite my best efforts the engine is experiencing rough cold starts (@ 12-20 C). Symptoms-wise, it's pretty cliche; no codes, engines feels like it's missing here and there from start until it warms up; a bit of a chassis rumble and a slight backfire-like sound when it misses. Once warmed up, the engine is rock steady at idle. Warm restarts have no issues. I'm just a hobbyist, and I'm still getting the hang of this platform along with all the tools. I would've liked to include a couple datalogs below from MHD, but sorry this forum won't allow me to share the any HTML. As far as I can tell my lpfp and hpfp are running well within spec. But if I were to guess, I'm suspicious of my bank 2 pre-ct O2 sensor. I wouldn't ever ask anyone to figure this out for me, but I wonder if I might ask for help on how to go about diagnosing this problem further? Thanks!

Just the Pertinent Details:
Original stock N54, odo ~82500, filled w/ Chevron acn 91 (I know)
MHD Stage 2+ ots tune
XHP Stage 3 v3.0
New Genuine Index 12 injectors (calibrated via INPA) x6
New Eldor coils x6
New NGK 95770/5992 (Step 1) plugs, gap 0.22 x6
New vacuum hoses and hard lines throughout
New gaskets and coolant hoses throughout
New VTT Stage 1 turbos, PCV valve, inlets + outlets
VRSF 5" intercooler
VRSF Charge pipe
Tial BOV connected via BMS BOV vacuum adapter
Ct-less down pipes
New Pierburg boost solenoids
New Genuine vanos solenoids/filters
New Genuine MAF sensors
New Genuine camshaft sensors
New Genuine crank sensor
Walnut blasted intake
All new fluids

Last edited by KAR; 12-01-2021 at 12:15 AM..
Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

vBulletin Skin developed by: vBStyles.com
Copyright 2007 - 2022, JB4tech.com