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BMW M50 Hall Crank Sensor Setup Help!


Tye

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Hi everyone,

I have a M52 engine that I converted from OBD2 to OBD1 so I could run a Link G4+ PNP. 

Today I was having trouble Calibrating the M50 OBD1 VR crank trigger on the front of the timing cover. 

Since I have an OBD2 block which still has the stock Hall effect Crank Sensor on the side of the block, I was wondering if anyone has used this sensor instead of the OBD1 sensor on the timing cover.

I think the rear trigger wheel on the M52 crankshaft has a 60-2 tooth design just like the M50, except smaller diameter and uses a Hall effect sensor instead of a VR sensor.

If anyone out there can help me configure this, that would be great!

Thanks in advance!

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Either should work fine, it would just be a matter of changing trigger 1 setting to hall and turn the pull-up on.  However, Im curious why you say "i was having trouble calibrating the VR trigger", what problem did you have?  Whether you use hall or VR you will still need to do the same calibration.

From memory the M52 may have the odd cam sensor that doesnt work.

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9 hours ago, Adamw said:

Either should work fine, it would just be a matter of changing trigger 1 setting to hall and turn the pull-up on.  However, Im curious why you say "i was having trouble calibrating the VR trigger", what problem did you have?  Whether you use hall or VR you will still need to do the same calibration.

From memory the M52 may have the odd cam sensor that doesn't work.

Sorry I should have been more clear about the VR sensor. My main point of this post was to see if anyone has used this hall effect sensor and how to set it up. Since I have a perfectly good one hanging out on the side of my block.

Anyways, When I was doing the trigger calibration with a timing light. I had the timing locked at 0 degrees and hooked up a timing light to read off the green wire on the Cylinder 1 coil pack. I noticed that the timing seems to be around 30 degrees BTDC when looking at the trigger wheel. I Raised the trigger offset value gradually until I saw the timing at around 0 degrees on my timing light. Oddly enough, when reving up the car to check for timing drift, the motor started backfiring out the intake and started building way more boost when free-reving, almost like the timing was now excessively retarded. The timing also drifted to what looked like 90 degrees on the timing light. This made me question my timing light.

Aside from all of that, I wanted to use the hall sensor on my block since they provide a cleaner signal. 

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So, for wiring in a Hall crank sensor onto an M50 harness. The M50 ECU Plug has  2pins for the VR crank sensor.

Pin 16 is Crank sensor + Signal

and

Pin 43 is Crank sensor - Signal

For a 3 wire Hall sensor,

Do I just supply 5v and ground to common sensor supply wires and send the Hall signal through Pin 16 on the ECU Plug and leave Pin 43 Alone?

Also planning on using shield cable and grounding the ECU end of the wire to a common shield ground pin.

 

Sound correct?

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4 hours ago, Tye said:

Aside from all of that, I wanted to use the hall sensor on my block since they provide a cleaner signal. 

A VR sensor is actually superior to a hall sensor in almost all aspects, the only real negative is a low voltage output on some engines that crank slow.  It is more accurate from a timing perspective and far less suseptable to noise.  Having said that either should work ok - just you are going backwards by changing to hall.  As I mentioned earlier Im pretty sure the M52 has a funny frequency based cam sensor so that is probably what is causing the trigger error - not the crank sensor.

Your ECU has a trigger scope built in so rather than change parts for no reason, it would be wiser to use the scope to see what is wrong.  You can post the trigger scope capture here for advice.

 

3 hours ago, Tye said:

So, for wiring in a Hall crank sensor onto an M50 harness. The M50 ECU Plug has  2pins for the VR crank sensor.

You already have ground and signal, you just need to run a new wire to supply power to the hall sensor.  The power wire does not need to be shielded.

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On 3/30/2019 at 2:33 PM, Adamw said:

A VR sensor is actually superior to a hall sensor in almost all aspects, the only real negative is a low voltage output on some engines that crank slow.  It is more accurate from a timing perspective and far less suseptable to noise.  Having said that either should work ok - just you are going backwards by changing to hall.  As I mentioned earlier Im pretty sure the M52 has a funny frequency based cam sensor so that is probably what is causing the trigger error - not the crank sensor.

Your ECU has a trigger scope built in so rather than change parts for no reason, it would be wiser to use the scope to see what is wrong.  You can post the trigger scope capture here for advice.

 

 

Oh really? I was under the impression that Hall sensors are superior in every way. Hm.

Im running the M50 Hall cam sensor which is currently working really well for me.

I never actually had a trigger error. In fact my car is actually running really well!

I was just having issues calibrating the crank trigger. The untouched M50 PNP trigger settings showed 30degrees BTDC on my timing light at idle and drifted to around 90degrees BTDC when free revving to 4000-5000rpm. I changed the trigger offset on PC Link and was able to get the idle timing to about 0 degrees on the timing light. The car still ran, just felt very sluggish and felt like it was lacking timing. It built boost really easily free-revving and lost a good amount of throttle response.

 

Is it possible that I have a bad timing light? Im using a Centech harbor freight one and clipped the lead around the green wire on my Cylinder 1 Coil pack.

Ill post a trigger scope later today!

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4 hours ago, Tye said:

Is it possible that I have a bad timing light? Im using a Centech harbor freight one and clipped the lead around the green wire on my Cylinder 1 Coil pack.

I would say that is possibly your problem.  Many timing lights will fire off the dwell edge rather than spark edge when connected to the primary side of the coil.  The correct way to check timing on a COP engine is to pull the coil out and run a short HT lead between the coil and sparkplug, with the timing light attached to that.

Something like this:

8JuXjJr.png

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