MHD- Constant Codes + cold start stalling

[MeAndMyMR2]

Good day everyone,

I am rather new to the forums but not to BMW issues so i thank you for your time!

I have a 2011 135i 6sp convertible with the following mods and issues.
VRSF catless DP, 5" FMIC, and CP
Mishimoto oil catch can
MHD stage 1+/2 flash tune
new bosch oem plugs gapped.
new map sensor

2BC0 - Mixture Control Fuel Air mixture too lean
2BF4 - Rail Pressure sensor plausibility: Pressure too high before engine start.
2C42 - Mixture control multiple fault

These codes are followed by the occasional stalling during a cold start or at red lights (unless i raise idle in MHD). These codes started after modifications obviously but from my research the mods i have installed shouldn't really cause any issues.

I currently am leaning towards O2 sensors or some sort of fueling issue. Stage 2 only shows max 11psi tapering down to 8-9 during WOT 3rd gear pulls. Timing corrections are semi-rare at 2-5 degrees on one or two cylinders. IAT is generally within 20 degrees of ambient temp. No misfires recorded or felt.

I am looking to install Pure S2 turbo, upgraded fuel pumps, PRW coil packs, NGK one step colder plugs, and replace the diverter valve if needed. Maybe Meth oneday but would like to sort the lean/mixture issues first.

Thank you in advanced for any help!

[iminhell1]

Why new MAP sensor?

I really doubt it's an O2 sensor. Odds are far higher it's due to the parts you just put on.
Boot leaking at the intercooler would be my bet as to the boost not being on par.

The fuel stuff sounds like the rail sensor took a dive. But that seems like really odd coincidence. More likely something in the tune not being correct.

[MeAndMyMR2]

Map sensor was replaced just as precautionary measures as well as an older code i got when the car was first purchased. The post cat o2 is new because the original is stuck in the cat. When i went to vrsf catless dp i installed a new post cat, and today installing a new precat sensor. The originals will remain in the OEM Catted DP.

I was thinking the fuel pressure sensor as well as some of the numbers were wonky however it seems to be working. 2000-2200psi cold start, tapering down to about 7xx at warm idle. Fluctuating 1200-1800 under medium load. logs can be provided if needed.

MHD Suggested going to stage 0 and retesting everything which is fair, however if i dont get the same results does that mean i need a different tune/company? When i do the Pure Stage 2 turbo and supporting mods i will be getting a custom tune so that should help.

[iminhell1]

Get a good running car before you modify. That's rule #1.
Rule #2 is step back. If there is a problem after a modification, take the mod off, or go back to stock tune. Never beat on a malfunctioning car, if you value it.


Replacing a MAP is not a precaution. And there are only about 3 codes I can think of that would say for sure a MAP is dead. Anything else would point to a wiring issue or a vacuum/boost leak.

In my case, I can't log with MHD from key turn through startup. If you can, do a log like that. See what LPFP and HPFP are doing. If it's kicking a code it's saying there's a problem directly with the fuel system. Not a MAP, not an O2, not anything else. LPFP sensor, HPFP sensor and associated.

[MeAndMyMR2]

As mentioned the car was running fine and does continue to run fine now after the cold start. She pulls strong with no CEL. I just want to eliminate the aforementioned codes. I will check the LPFP and HPFP during startup this weekend. The MAP was bad originally that's why i replaced it. I have tripled checked all intercooler piping but i have my doubts with the seal on the vrsf charge pipe where it connects to the intake manifold/throttle body. The problem is that my oem charge pipe is damaged and will not seal at all (hence why it was replaced).
You dont think that the o2 sensor is what tells the car its leaning out? could it just be a wiring issue? how could i check? resistance or something between point A and B?

2BC0 - Mixture Control Fuel Air mixture too lean
2BF4 - Rail Pressure sensor plausibility: Pressure too high before engine start.
2C42 - Mixture control multiple fault

These codes to me say either fueling, dme, or o2 sensor. However i am not an expert. I can put the cat back in once it warms or for my next inspection. I will let you know how stage 0 runs and log cold start on MHD.

[iminhell1]

I have no occurrence data with the codes. Did the 2bc0 and 2bf4 happen at the same time? Where they minutes apart? Etc.
You'll need to find that out. Could be all happened at once and are due to 1 faulty part. Or could happen at varying times and be multiple parts failing. A log really isn't going to tell you here I feel. This will come down to component testing; which the BMW service software can do (ISTA-D).

[MeAndMyMR2]

If i recall correctly they all occur at the same time. Generally at a cold start. the Mixture control multiple fault and mixture lean sometimes happened during heavy acceleration if the cold start was say above 65-70F. But lately (in NY) a cold start is 28-38 degrees and the codes show up after the rough start/stall. I turned off the cold start noise reduction and it helped alot. At this time i am leaning towards MHD tune issues. I will component test tomorrow with ISTA if the rain holds out.

[PopsnBurbles]

I had the same set of codes when I had an aftermarket intake on. I put the stock one back on and the codes disappeared. Im not sure if this is relevant to your case but I hope it leads to something for you.

[Alturiak]

Was there ever a resolution to getting these codes sorted out? Currently dealing with the same ones... would love any data on what fixed yours if possible

[MeAndMyMR2]

Car has been driving fine with the same codes since modification. Even now with no catless DP running stock OEM tune I am getting DME-2774 and 2BEA with a low idle and stalling at red lights during warm/hot days or runs.

Thinking its time to replace the Valvecover & Gasket as its getting brittle and old. Will update following the maintenance.