[OEM+Alpine]

Hey all,
This isn't a typical "what should I do request" - I am looking for help to determine what am I missing.

BACKGROUND:
- I have a 2015 335i (N55) with 62K miles
- Spark plugs were replaced 4K ago
- I have a CTS turbo charge pipe but on 1K miles ago (Drove the car for a while with the charge pipe before MHD stage 1 and no issues)

ISSUE:
- When I loaded MHD stage 1 from the first pull after loading the software the "drivetrain malfunction" light came on
- When reading the code it's 120308 (shown below)
- The car doesn't buck or go into limp mode
- When the issue is cleared it will resurface during WOT at high RPMs only
- It happens whether in drive or sport along with comfort or sport plus drive settings
- There also is an 801C20 code but I'm not sure if that's unrelated
- I messaged MHD and they were no help

STEPS FORWARD:
1.) Flash back to stock and see if the issue persists
2.) Flash stage 1 again and see if this issue persists
3.) Depending on above then I'll start looking at the chargepipe connections again
4.) After that smoke test?

Thanks all,
Jason

[thejeremyman9]

I would say before you even flash back to stock you need to log. Make sure you go through the parameters and turn nearly everything on. Then upload your log to datazap and post it for us. Did you send a log to MHD already?

Did you log at all prior to install or tune? What i did was: log stock car --> install IC+CP and log again --> flash stage 1 and log again. The idea is to have logs before and after any hardware or software change so you can easily determine when an issue started, although it may be too late for you now, consider that for future changes.

If you aren't familar, you need to do the log in 3rd if 6MT or 4th if 8AT, start at about 2000 or 2500 RPM, floor it (dont roll into it) and log until about 6k or 6500 rpm and stop the log. Get maybe 2 logs like that. A 1-2-3-4 log is also helpful if you are trying to determine if you have a boost leak, since the high load in 4th sometimes allows you to reach target even with a small leak.

If you want to real about all the issues i had with boost leaks and how i found them/fixed the, check out the Oring thread and boost leak tester thread. Let me know if you can't find those (late 2019).

So here's what i would do:

1. Capture logs described above, upload, and post here.

2. Potentially reset adaptations (except battery) through MHD app, drive around for maybe 20 miles under varying conditions, then log again and see if any difference.

3. If cost still arises, follow your steps and check for a boost leak.

[bennybeam]

hi, have you figured out what's wrong with it yet? I am experiencing a similar problem, and I think it's the diverter valve.

My setup: f30, n55, currently at 73k miles, vrsf fmic, cts turbo intake, cts charge pipe
Maintenance: coil and plugs done at 63k. coil change always b4 5k
MHD: I tuned MHD for about a week now, stage 1, 93 oct, burbles only set at stock 0.7s in sport mode, start up roar, everything else I kept stock. (I kept most of it as stock as possible I only wanted the HP, and never really cared about the pops and bangs)

Situation:
doing a launch from dig, went up to 4th gear and around 5k rpm, the check engine light with code (120308 - Charing pressure control, plausibility, pressure too low AND 118401 - Mixture control: Fuel- air mixture too lean, large deviation) light came on. but I don't feel power loss at all so no limp mode, just the light.

My diagnosis:
I immediately went home, ripped the underbelly off the bottom of my car, and checked for any cracks/misconnections on parts I had ever touched. Fmic, charge pipe, and intake, spark plug, coil. Then check for oil leaks at all possible weak points: valve cover, oil filter housing gasket. I concluded nothing was cracked or leaking, no burning oil smell.

I then took it out for a test drive. when I drove it moderately (semi-pushing it up to around 4/5k rpm), I pressed the gas pedal, the turbo spooled up and picked up speed like normal. But when I took my foot off, I heard the turbo spool down sound for maybe a millisecond or two longer than it used to.

So my guess is the diverter valve. if someone has a difference of opinion pls feel free to reply to me. thank you

this guy had a similar experience https://x3.xbimmers.com/forums/showthread.php?t=1790375

[thejeremyman9]

Originally Posted by bennybeam

hi, have you figured out what's wrong with it yet? I am experiencing a similar problem, and I think it's the diverter valve.

My setup: f30, n55, currently at 73k miles, vrsf fmic, cts turbo intake, cts charge pipe
Maintenance: coil and plugs done at 63k. coil change always b4 5k
MHD: I tuned MHD for about a week now, stage 1, 93 oct, burbles only set at stock 0.7s in sport mode, start up roar, everything else I kept stock. (I kept most of it as stock as possible I only wanted the HP, and never really cared about the pops and bangs)

Situation:
doing a launch from dig, went up to 4th gear and around 5k rpm, the check engine light with code (120308 - Charing pressure control, plausibility, pressure too low AND 118401 - Mixture control: Fuel- air mixture too lean, large deviation) light came on. but I don't feel power loss at all so no limp mode, just the light.

My diagnosis:
I immediately went home, ripped the underbelly off the bottom of my car, and checked for any cracks/misconnections on parts I had ever touched. Fmic, charge pipe, and intake, spark plug, coil. Then check for oil leaks at all possible weak points: valve cover, oil filter housing gasket. I concluded nothing was cracked or leaking, no burning oil smell.

I then took it out for a test drive. when I drove it moderately (semi-pushing it up to around 4/5k rpm), I pressed the gas pedal, the turbo spooled up and picked up speed like normal. But when I took my foot off, I heard the turbo spool down sound for maybe a millisecond or two longer than it used to.

So my guess is the diverter valve. if someone has a difference of opinion pls feel free to reply to me. thank you

this guy had a similar experience https://x3.xbimmers.com/forums/showthread.php?t=1790375

Datalog?

You might just be hearing the DV more because you are running more boost.