318i e46 MAF, ECT & TPS reference/grounding problem

[Venhengu]

Guys I'm new around here. My 318i e46 manual has starting issues with MAF plugged in. Engine temperature goes to the high extreme and it won't start. With MAF disconnected the car starts but has challenges maintaining a good Rev count. Thank you in advance. If this issue has been dealt with before, may you kindly direct to the thread!

[MarcoZandrini]

The first step in diagnosing a problem is to scan the engine computer (DME=digital motor electronics) for codes. Unplugging the MAF causes the DME to use an overly rich fuel/air mixture. I’m betting you have vacuum leaks. Have the intake smoke tested.

[Venhengu]

The first step in diagnosing a problem is to scan the engine computer (DME=digital motor electronics) for codes. Unplugging the MAF causes the DME to use an overly rich fuel/air mixture. I’m betting you have vacuum leaks. Have the intake smoke tested.

Thank you for response.
Diagnosis said "hot film reference voltage"

[MarcoZandrini]

That refers to the MAF. Google “BMW E46 hidden OBC functions.” Test #9 shows the voltage as seen by the engine computer (DME- digital motor electronics). Check and report back the OBC readout when the:
- ignition is in the run position with the engine off
- engine idling - engine revving at 2000rpm.

Whacky voltages cause whacky issues. How old is the battery?

With the car off, remove the MAF connector. The connector is made of 2 halves: the chassis harness and the MAF. One side has pins and the other side has sockets. The pins and sockets need to have “intimate” contact. What can happen is the sockets widen up and loose that contact with the pins.