Sync loss problem

[ngaio75]

Hi,

I have a sync loss problem which is proving to be elusive. I have a MS3X controlling a V6 with batch fire injection using the two outputs from the MS3 mainboard, and wasted spark using three ignition outputs from the MS3X board. The engine has a factory 60-2 crank wheel and sensor and no cam sensor. I'm using a DIYautotune quad spark unit driving a Ford coil pack.

The tooth log and composite log are all good when cranking with spark and injector power but the fuel pump fuse out. With the fuel pump fuse in, the engine starts but pulses up and down on idle, and composite log shows continual sync errors. The sync error reason is 2 (missing tooth earlier than expected), and counting the pulses in the composite log I seem to only have 57 teeth instead of 58. The tooth log looks fine apart from appearing to have on 57 teeth.

I haven't had the engine running on this set up so have guessed the VE table. Attached are logs with the advance set fixed at 10. Anyone seen this problem before that can point me where to look?

Thanks
Mike

[Matt Cramer]

Can you post a tooth log? These are often easier to interpret than composite logs for a 60-2 pattern.

Also, have you tried turning off noise filtering?

[billr]

Are you adventuresome? Try setting 60-3.

Edit: is this a VR crank sensor?

[ngaio75]

Hi,
Thanks for your feedback. I have been unable to work on the car for a couple of months but back to it now and took the opportunity to purchase a cheap oscilloscope. I tried 60-3 which was a bit better but still had some sync loss. Sensor is a factory Bosch VR sensor.

Attached is a view from the scope connecting to TachSelect and TSEL. It seems that the MS3 is missing the tooth immediately after the missing teeth due to a low amplitude signal for that tooth from the sensor. R52 and R56 are turned fully anticlockwise so and noise filtering is off. This is cranking with the fuel pump turned off.

Any ideas on how to either increase the signal for that tooth or increase the sensitivity of the circuit to pick that tooth up?

Thanks
Mike

[billr]

Yes, I have seen this issue. See my last post in this thread:
viewtopic.php?f=131&t=60106&p=451582&hilit=60+3#p451582

[ngaio75]

Thanks billr. I see you suggest in another post filling in the missing teeth as a possible fix but if there isn't a ms software or simple hardware fix then I might try swapping for a Hall effect sensor as from what I can tell that may work better.
M
I'm disappointed that an OEM sensor with an OEM toothed wheel obviously works on the OEM (Motronic) ECU but not on the MS3, but I guess that's the benefits of a specific ECU for a known vehicle config vs a single design trying to accommodate a wide variety of sensors.

For future reference engine is an Alfa Romeo 12V 3L.

[dontz125]

R52 and R56 are turned fully anticlockwise so and noise filtering is off.

Any ideas on how to ... increase the sensitivity of the circuit to pick that tooth up?

For all we caution people about the MegaManual when using MSExtra code (of which MS3 is a version), the original B&G manual does have some hardware information that I can't find in the Extra manuals. This I would suggest is one such case.

Look at the page in the MegaManual on Adjusting the V3 Pots. Unless what I'm misreading it, turning R56 a few turns clockwise should help. You may also need to adjust R52.

[93supercoupe]

I adjust pots r56 and r52 all the way out on most all installs i do with a 60-2 config.

I had one this weekend picking up crank errors only at idle and that was fixed by adjusting the pots "full out"