M3 3.0 Camshaft sensor help

[KwS 2378]

Hi all.

I have a 94 3.0 M3, with S50B30.

Its been running well until last weekend, where i noticed the idle was a bit rougher than usual but still drove OK. I took the car to work today, and on the way home it decided it was sick of running OK, and started to bog down badly (like coming completely off the gas) under any load, yet it would rev out OK unless loaded.

I moved it into the garage when i got home, it then decided not to start. I fired up DIS, and came up with code 17, camshaft position sensor phase detection not plausible. Obviously theres an issue with the "camshaft position sensor", but as the car has 3 sensors that monitor the camshaft (TDC in the middle front, and one for the intake and one for exhaust) i dont know which one has failed. I removed all of them, noted the intake sensor was really dirty so cleaned it, but although the car starts (after a bit of cranking) it runs like a dog when under load, and idles a bit rough.

Has anyone had this before, and know which sensor it is? Dont really want to go out and buy all 3 sensors, at $100 a pop in order to narrow it down.

[KwS 2378]

All sensor resistances are within tolerance too

[KwS 2378]

It still runs, idles OK, maybe a little rough and can be driven but it misfires badly and almost cuts out under load.

The code DIS gave specifically said Camshaft sensor, and said the camshaft position was not plausible.

Plugs are OK, coils although old appear OK. Cleared codes, went for a drive and sure enough the camshaft sensor error returned.

I think i can eliminate the intake cam sensor (behind the sprocket) becuase it gave an accurate reading when i did the vanos test yesterday. Its either the sensor on the front or the sensor on the exhaust cam. If i can get a wiring diagram for the DME and VNC i should be able to narrow down if the DME uses the exhaust sensor, or if its only for the vanos control unit.

Edited August 30, 2014 by KwS