2008 X3 Engine stall/misfire/lean after shampoo

[yogopo]

After an engine shampoo (with hose not pressure washer) car start and idle rough (rpm up/down).
If revving gently- rpm goes up and no issues.
Deceleration to a stop nearly causes a stall and sometimes does stall.
Codes found- various banks misfire, bank 1/2 lean.

Tried: drying out all coils and numerous electrical connectors under hood. Checked and cleaned MAF with MAF spray.
Used electrical contact cleaner to for connections. Checked cabin air filter area- dry.
I'm a backyard mechanic and have engine shampooed various cars in many years and never had such an issue.
Please help.

[bmwdirtracer]

BMWs are extremely good about having the engine washed - I do this without any hesitation to a BMW motor (and I NEVER wash a VW, Audi, or Volvo engine!)

Therefore, I'd be 90% certain that you've accidentally caused a fairly large intake air leak. If a visual inspection does not imediately reveal the culprit, I highly recommend that you take the car to a good Euro shop, and have the intake/ccv system smoke tested.

[yogopo]

Thanks, I'm about to try running the car with maf unplugged, perhaps an o2 sensor as well?

- - - Updated - - -

Update:
I disconnected the MAF sensor and the car runs fine - aside from slightly jerky downshifts.... need I still check for air leaks at the runner/intake?

[bmwdirtracer]

Well of course...what you've done is confirmed that the air/fuel mixture is wrong, when in closed loop. And, in a BMW, 85-90% of the time, that means an intake system leak. A smoke test with a pro smoke machine is the only reliable test; spraying flammables is about 20% effective....and dangerous.

[yogopo]

Thanks again!