Cam sync near missing teeth

I tried enabling cam sync on a early BMW M50 non-VANOS engine with bad results. I used a Honeywell GT1 Hall sensor since this engine has a VR sensor, only the VANOS engines have a Hall sensor but we had none of those and the GT1 is a drop-in replacement (needs a 4 mm shim to get 1 mm distance to tooth).

First off, to the believers in "keep it simple stupid" : If we ignore the fact that this engine can run perfectly fine with dual-out and "wasted spark", I feel this is an irritating issue that should have a solution or anwer.

Is this related to what's written in this forum thread :

Here is a log file, triggerlogs (rising + falling) and the pictures below.

Right at about 3500 rpm the sync just goes crazy. I might have a hardware problem here with the sensor not detecting it properly, but the sectrig position doesn't make much sense. It's rock solid at 26.7 or 28.1 degrees at all other times up to that point. I have a hard time seeing that there is suddenly a lot of slop in the cam chain drive. So it could possibly be something with the sensor.

Here are the triggerlog pictures from cranking the engine that show that the camsync tooth appears right at the missing teeth gap on this engine.

Falling edge (the better choice: more than 4*6 degrees from tooth0)


Rising edge