MoTeC Global Forum

Hey,

I am working on a BMW M42 engine right now. It has two magnetic sensors, a 60-2 trigger wheel on the crankshaft and a one tooth trigger wheel on the camshaft.
I tried Ref/Sync Mode #7 ("two missing twice per cycle) but the M880 did not get synced.
Next I tried mode #68 and the ECU syncs now. Is that the correct mode for that engine? Why did mode #7 not work?

find attached a ref/sync capture screenshot...

Thank you!
Robin

Mode 7 is correct. What is that big rise on signal level middle of pic? Shouldn't be like that.

PQatPIT wrote:Mode 7 is correct. What is that big rise on signal level middle of pic? Shouldn't be like that.

It does not look like a Hall signal.
I think that the magnetic signal has a voltage that is correlated with speed.
The x-axis does seem to have some slightly closer spaced trigger signals where the voltage seems high.
So maybe it is OK?

its a mag signal, and it rises with encreasing engine speed which is normal during cranking.
but why does mode #7 not work? is it because the sync signal doesn't come in a certain window refered to the ref tooth (180°+-70°)??

thank you

When in configuration phase I usually do ref/sync capture with no spark plugs. This way the engine speed fluctuations are minimal and it gives a clue about sensor level. Next step is to put spark plug on no.1 cylinder and do ref/sync capture again. It gives a clue where CrIP is about.

That much rise on signal level tells me that one plug is missing, some cylinder is not sealing properly or at all, or something similar. May also be that trigger wheel is not concentric or sensor is aging or failing. BMW sensors age slower than other brand cars but they are not eternal . If mode 7 is not working then maybe setup is not correct?

The timming is correct.. your sync is occurring within the window timming size of 7 ref/sync mode.

Could you put the print screen of yours setups?
Which more errors you got beyond the "no sync"?


M42 is very easy to get synced.. M44 is much more boring.


Regards,


Matheus

Was trigger edge selected correctly?
Ref = falling
Sync = rising

Definitely Mode 7 with falling on the Ref and rising on the Sync. Make sure you have your mag level tables set sensibly. All in all you need to watch my ref/sync webinars.

As was said earlier if you are sure it is set up correctly and still won't sync you can pull the plugs out and try that. If it syncs then you will need to modify the Tooth Ratio.

Hey guys,

unfortunately I didn't have time to do further tests yet.

But why would you setup falling edge on the the ref sensor? I setup rising edge for both sensors after what I learned in the webinar? Both signals look the same to me...

thanks for your help
Robin

But why would you setup falling edge on the the ref sensor? I setup rising edge for both sensors after what I learned in the webinar? Both signals look the same to me...

The diagram near the bottom of this page helps visualise the reason:
http://www.megamanual.com/ms2/wheel.htm

This example is only one missing tooth but the same prinipal applies. Note that falling edge gives the correct result (ie. the time period between trigger edges is 2x normal at the missing tooth). If you set it to rising edge the ecu would not acually see a missing tooth but instead two slightly longer periods.