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DISCUSSION => Engine + Driveline => Topic started by: 1998ccc on November 30, 2015, 02:36:00 PM

Title: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: 1998ccc on November 30, 2015, 02:36:00 PM

Recipe:

1997 M44 short block / lower case / timing chain components.
1991 M42 head and cam sprockets
1991 M42 intakes and oil pans
1991 M42 fuel injection.



Everything is 1991 e30 m42 except I want to use the M44 bottom end and timing case.  I can't seem to find a DIY on running the rear mount crank sensor.  Is the M44 sensor plug and play into the 91 M42 harness?  Is the m42 one too short to mount @ the back of the block?  Pin location correct for m44 sensor if it works in the m42 harness?? Would rather go that route vs. changing to early m42 case / fabing a front crank sensor mount etc. 

Thanks for any help.

Title: Re: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: benz-tech on November 30, 2015, 11:10:44 PM

The m44 sensor is not plug and play into the m42 harness. But iirc, they are both 3-wire, 5v hall sensors. The problem is that the tabs don't line up correctly from the sensor to the m42 harness. I was ready to take this route but decided to run m44 electronics

Title: Re: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: locknload on December 03, 2015, 08:55:51 PM

I think I would go to a JY and get an M44 crank sensor socket (the female fitting) and an M42 crank sensor (bad is fine) and fabricate an "extension cord" if you will, so you can use a stock M44 sensor, but with the extension, plugs into the M42 socket. 

As an aside, may I ask what's driving the desire for this frankenmotor?  The M42 block is supposed to be superior to the M44 due to its forged internals.

Title: Re: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: benz-tech on December 04, 2015, 12:02:35 AM

There's only a handful of these running, to my knowedge, so i don't think theres any mass rush to build one. But, i guess, Frankenmotor: Because 1950cc's, 11:1, better oil pump, better electronics, and... its comparatively inexpensive to accomplish the aforementioned feat with all oem parts.

Title: Re: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: bmwman91 on December 06, 2015, 12:55:18 AM

Just FYI, the M42 uses a variable reluctance (VR) sensor for the cam and crank position. If the M44 uses a Hall effect type sensor, then you cannot interchange them. If you want to run the M42's M1.7 DME, you will need the M42 sensors to go with it.

Title: Re: M44 Rear Crank Sensor with 91 M42 Electronics
Post by: 1998ccc on December 09, 2015, 02:27:15 PM

I found a low mile (57k) wrecked Z3 too cheap to pass up.  I already have an extra 1991 M42 with lots of miles for all of the swap bits. M42 head will be freshened or I could swap complete M44. Most people steer u in the direction of the M42 head vs. the M44.  Car will be part time driver as well as a couple drivings schools a year.