2009 BMW 328XI E90 N52K Engine -- dreaded P0171 /P0174 codes - advanced help needed

[rodneybarrett]

Hi, First time posting here so be gentle. I have read posts from this forum and many others over the past 3 weeks trying to determine my particular issue. So, needless to say, I have tried finding the resolution myself. I also know when I need help, hence, this post.


Symptoms:
P0171 and P0174
Gas mileage terrible
Long Term Fuel trims around 24%
Short Term fuel Trims around 27% at idle but at 3-5% above 1500 rpm



Things already checked/performed:
- Tested Fuel Pressure - 72 PSI, right where it needs to be
- Smoke Test, found leaking VCG - replaced VCG (now that was a project),
Performed smoke again and no leaks at all. Also short term fuel trims, banks 1 and 2, are between 3 and 5%, with a strange spike every so oftern. Long term around 3%, however the long term % could be because of erasing values when battery was disconnected.
- Checked DISA valve, not broken and closed when off.
- Replaced air filter
- Have cleaned MAF sensor 3 times, no luck.
- recently replaced spark plugs(NGK) and coils (delphi coils)
- Have taken out oil cap, has slight suction but nothing major. When I do put it back on, I hear whistling/vacuum leak but goes away after a few seconds. I am justing assuming this is the vacuum reestablishing in the crank case.


I guess the following are likely candidates but will need help on best approach:

- Injector issues, needs cleaning or replacing
- MAF Sensor bad and needs replacing
- CCV on valve cover bad (but would it cause these codes?).
- Vanos Solenoids?

BTW, engines idles great at ~650rpm, performance doesn't seem off at all except for fuel economy.
also, about 1 month ago, Had bad stuttering on cold start but that went away(yes, does seem kinda of strange that goes away and then lean codes come up). This was also before I replaced the VCG too.

So, any help form the forums would be greatly appreciated.
I am the kind of person who won't let this go until I get to the bottom of it.

thanks.

[MIKYZZ4]

If you have smoke tested the intake system, don't forget the CVV, and the fuel tank ventilation system for leaks.
The worst case scenario might be eccentric cam sensor.

[rodneybarrett]

Well, I feel a little stupid now. I did all the hard work replacing the VCG and thought it wasn't fixed. The issue was user error. I had not properly cleared the previous faults. On my software, torque Pro (or maybe it is a BMW thing), the engine needs to be off to clear previous faults. Once I did correctly clear the faults and started the car, the Service Engine Soon light went off and all measurements look great. SES has not come back on. At least for now, I was able to fix my P0171/0174 lean codes issue for 4-6 hours of my time and around $70 for all the gaskets. And learned a lot about the vehicle in the process.

Hoping this help others. I will mark as solved.

[RocketSurgeon]

Hey since you have torque, I assume you're running android. I can give you the Carly .apk if you want. It has some pretty advanced BMW specific diagnostic and coding capabilities, and it should work with your existing bluetooth plug.