Fellow 50i owners, how many pins are in your MAF connector plug?

[KCG]

Would any 50i owners mind checking to see how many pins are in your MAF connector plugs?

My MAF connector plugs were replaced by an indy a while back when they tried to diagnose a lean code after the turbo inlet duct replacement. They could not figure it out and eventually give up. Turned out it was clogged air filters, and the MAF sensor on bank 1 went bad. I went ahead and replaced the filters and the MAF for both banks.

Since then, my x5 started having rough starts and cold crank hesitations. I took the car to the dealer and other indy shops, but no one could figure out what was going on because the car was not throwing any codes, and everything was tested fine, including the injectors.

After tossing multiple parts at it, from o2 sensors to ignition coils, spark plugs, air filters, and CCV, I was finally able to narrow it down to either the MAF sensors or the MAF connector plugs. I started the car with the MAF connectors unplugged, and voila, the rough start and cold crank hesitation disappeared. I tested it multiple times, and the issues only appeared when the MAFs were plugged in.

The MAFs are only a year and a half old. So I wanted to see if the connector harness were the issue.
Looking at the plugs, it appears this is a 4-pin connector.

(BMW) (8 509 441-01)
(BMW) (8 509 441-02)

I did some research, and the connector wiring diagram is as follows:

1. 12 Volt Feed Positive Power
2. MAF Wire Ground
3. MAF Signal ground
4. MAF Signal

Looking at my connector, it seems like I'm missing pin 3, the MAF Signal Ground. Is this how it was supposed to be, or is it just mine?

I also looked up the BMS 50i stage1 tune, and the connectors are all 4 wires.

If any 50i owners could check and confirm this, I'd be greatly appreciated it.

Thank you!

[Chilled]

M here, same P/N for the MAF sensor and only 3 pins on the connector. Pin 3 is missing on both sides.

The doco seems to have 2 different plugs versions of the 4 pin plugs. Some have 4 active pins, and some only 3.

[KCG]

Originally Posted by Chilled

M here, same P/N for the MAF sensor and only 3 pins on the connector. Pin 3 is missing on both sides.

The doco seems to have 2 different plugs versions of the 4 pin plugs. Some have 4 active pins, and some only 3.

Thank you for the response! This helped me confirm that the connectors were okay. I went ahead and ordered a new set of MAF, installed and reset the engine adaptation with ISTA, and now all my fuel trims are back to normal at idle. Both banks are +/- 0% - 4% STFT & LTFT. The car seems to run a bit smoother as well.

At coasting, LTFT on bank 1 is running slightly lean at +8%. Before MAF and the adaptation reset, it was running rich at -10% - 14%. Sometimes there are rotten egg smells from the tailpipe. Now is gone.

Now I can move on to diagnosing this high pitch noise coming from the intake pipes, as well as studdering when accelerating/decelerating/coasting around 70mphs.