Need Mystery Vacuum Line Help

[Wturner5354]

2007 X3 3.0SI. Need help identifying routing from vacuum line that run from the top of a module between cylinder 5-6 coils. I cannot determine where the vacuum hose goes from this small canister/module. I think this missing line is the source of my rich/lean error codes.

Thank you

[dukedkt442]

Pictures help; if you are referring to the round CCV diaphragm attached to the top of the rocker cover between 5 and 6, no vacuum line attaches to its nipple.

For your codes: how do you concurrently have both lean AND rich codes? Do they vary by bank, or switch between rich and lean on each bank? More insight is to be gained by pulling and reviewing your fuel trims. That said, a lean condition on an older car is FAR more likely than a rich condition. Easiest first, look for any gasket that separates oil from atmosphere for the presence of leaked oil; an oil leak is a vacuum leak. If that is inconclusive, either smoke test it or propane test it.

On the N52, the most common sources of unmetered air are the rocker cover gasket, valvetronic motor gasket, oil-filler cap gasket, oil pan gasket, and the vacuum line that feeds the exhaust flap solenoid in the trunk. A soft-failing fuel pump will also run lean; pull your spark plugs and read them for lean idle conditions (when a vacuum leak is most discernable). If only one bank reads lean, you more likely have a misfire or O2 sensor issue, but if both banks run lean, it is probably an air-leak issue.

If you are running rich, you'll want to check for bleed-down at the fuel rail schrader valve; on the N52, pressure shouldn't bleed down more than ~5psi over 10-15 minutes IIRC. Pressure at idle should be ~70-72 psi. If pressure bleeds down, look for weeping injectors, either by reading the spark plugs or pulling the injectors and running a Key-on/engine off bleed down test.