Megasquirt PnP into Motronic 1.0 (it works)
Posted: Nov 10, 2013 7:37 PM
No further need for speculation about whether the stock speed/reference sensors could be used to drive MS. I just proved that it works.
I took my MS1 + Zeal Engineering dual-VR board, and wired it for the second sensor (I was using only one previously on my M20 w/ 60-2 wheel). Plugged in the 35-pin connector, IAT, and vacuum line, and my shark started right up and idled at 2000RPM (lulz)
I had eyeballed the old M20 parts sitting around my garage to try to figure out what the triggle angle would be. Using my powers of assumption, I made up some numbers that I thought would work for the M30. After removing the water pump pulley so I could find the darn TDC mark I checked it with a timing light. Turns out I was off by 22 degrees. After fixing that, it runs half-way decent with recycled M20 VE/spark tables.
The M30 flywheel has 116 teeth. The only problem with this is that it isn't divisible by 3. The MS1 spark timing algorithm depends on having 3 trigger points that are evenly spaced 120 degrees apart for an inline-six. With 116 teeth there are no such points, so I am using the closest possible teeth. This introduces an error in the spark timing of up to 1.5 degrees. This is not too bad and it could be fixed with a fudge factor in the code.
The trigger angles ended up being pretty close to what I was using with the front-mounted 60-2 wheel on the M20. In fact, maybe it was designed to be the same, but it will vary a bit depending on whether the electronics and software are setup to trigger on rising or falling edges. Since the flywheel is not a missing-tooth wheel, it can work with either polarity.
Wheel decoder settings:
base teeth: 116
2nd trigger enable: yes
2nd trigger active edge: rising edge
2nd trigger missing teeth: none
Trig Pos A: 13
Trig return Pos A: 28
Trig Pos B: 52
Trig return Pos B: 67
Trig Pos C: 90
Trig return Pos C: 106
Spark settings:
Trigger angle: 66
Cranking timing: trigger return
Cranking advance angle: 12
Note that the S14 has the same flywheel sensors and number of teeth. Since it only needs 2 sparks per rev instead of 3, there would be no issues. Same goes for an M10, if someone happened to fit a Getrag 260/265 onto one.
On the M20 flywheel, I count 137 teeth, which is again not ideal but it could most likely run.
I took my MS1 + Zeal Engineering dual-VR board, and wired it for the second sensor (I was using only one previously on my M20 w/ 60-2 wheel). Plugged in the 35-pin connector, IAT, and vacuum line, and my shark started right up and idled at 2000RPM (lulz)
I had eyeballed the old M20 parts sitting around my garage to try to figure out what the triggle angle would be. Using my powers of assumption, I made up some numbers that I thought would work for the M30. After removing the water pump pulley so I could find the darn TDC mark I checked it with a timing light. Turns out I was off by 22 degrees. After fixing that, it runs half-way decent with recycled M20 VE/spark tables.
The M30 flywheel has 116 teeth. The only problem with this is that it isn't divisible by 3. The MS1 spark timing algorithm depends on having 3 trigger points that are evenly spaced 120 degrees apart for an inline-six. With 116 teeth there are no such points, so I am using the closest possible teeth. This introduces an error in the spark timing of up to 1.5 degrees. This is not too bad and it could be fixed with a fudge factor in the code.
The trigger angles ended up being pretty close to what I was using with the front-mounted 60-2 wheel on the M20. In fact, maybe it was designed to be the same, but it will vary a bit depending on whether the electronics and software are setup to trigger on rising or falling edges. Since the flywheel is not a missing-tooth wheel, it can work with either polarity.
Wheel decoder settings:
base teeth: 116
2nd trigger enable: yes
2nd trigger active edge: rising edge
2nd trigger missing teeth: none
Trig Pos A: 13
Trig return Pos A: 28
Trig Pos B: 52
Trig return Pos B: 67
Trig Pos C: 90
Trig return Pos C: 106
Spark settings:
Trigger angle: 66
Cranking timing: trigger return
Cranking advance angle: 12
Note that the S14 has the same flywheel sensors and number of teeth. Since it only needs 2 sparks per rev instead of 3, there would be no issues. Same goes for an M10, if someone happened to fit a Getrag 260/265 onto one.
On the M20 flywheel, I count 137 teeth, which is again not ideal but it could most likely run.
