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Cranksensor scope question

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I work on a m30b35 engine with ecumaster. I take one scope from the Crankshaft sensor, but I don't know if this is a normal curve. The engine work fine, but in full throttle I listen knock with small ignition advance. This is the reason for this research. I have attach a photo from picoscope graf.

Thanks you,

Attached Files

Did you check with the built in scope of the ECU Master, or if you have any trigger error? Looks to me like the signal is pretty weak (I might be wrong, I am not familiar with those engine...)

It definitely doesn't looks right for a 60-2 toothed wheel.

I have attached a picture of what a correct trigger signal should looks like, according to what I read online!

Attached Files

Hello Frank,

Thanks you for your replay. The reality is that I expect to take a curve like your photo.I hadn't good ground to my picoscope. Finally I take the right curve, but I can see that the voltage is very high more than 20V (you can see the picture). I increase the distance of the sensor from 0,4 to 1mm but again the voltage is high. Also I find that I can choose a pull up resistor.

I have tried the built in scope, but you can not see many data.

Finally when I lock the ''angel ignition lock'' and check with the time light, when I revving up I see that there is a change of 3-4 degree this is normal, or it will be stay stable to zero?

Thanks you again

Attached Files

I don’t have a lot of experience with variable reluctance sensors, but I heard in the course that if the polarity of the sensor is reversed, it could make the timing drift at higher RPM. Maybe that’s what is happening here?

Also, if you look at the picture in my last post, the voltage of the sensor is about 20V Peak to Peak.

Have you tried reversing the polarity of the sensor and running it as falling edge?

I haven't setup an m30 but I have setup and tuned several other BMW engines from the same era. I have never tried using the crank ref sensor as rising edge. I always do falling edge, which I believe is the proper way with the almost every engine. Not sure the specifics on why but there must be a reason. haha It's worth a shot.

Also I think the input delay on the ECUMaster software is used to correct the timing drift that you are seeing. Try adding values into that until your timing stays stable when you rev the engine (when you have the timing locked)

Hope that helps!

+1 for what Kyle said. Falling edge is typical with a reluctor and that microsec delay makes quite a difference causing some timing drift.

Another source of timing change with RPM is if the ECU has an adjustable "Ignition Delay" parameter and it isn't set correctly.

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