MicroSquirt.com read only forum (Jan.15,2018)

I hope!

I've been struggling to get a reliable cranking rpm signal on my ducati 90 degree twin.
At first my problem was rpms that jumped from 0 to 50,000 and anywhere in between.
messing with cranking pulse tolerance seemed to help a little, like the first crank after burning and cycling power would be perfect, then back to bad.
rpm's were good 90% of the time with the plugs out. I then ground the single long tooth to a much shorter one about the width of the vr sensor.
trying all different settings and i was able to get reliable rpm about 30% of the time.

The fix for me was to update firmware to 2.905. This is a v1 microsquirt and I had the 2.880 code. I should have updated a long time ago!
That would have saved me a lot of tinkering. after the update, cranking rpms still jumped around, but only from 0 to 1500 or so..
adjusting the cranking pulse tolerance from 50% to 70%, and now I have rock steady cranking rpms, 10 times in a row now.
I will still try to put some diodes in the vr- wire just in case.

thanks to everybody here especially 24c, sqlguy, bruce and al. I have spent hours reading all of your posts, and i would have given up long ago without more knowledgeable people to explain everything along the way.

thanks again!

ok my microsquirt has a sick sense of humor. I dont know what has changed now, but I am unable to get a usuable rpm under any condition now..
i am giving up on vr sensors on this thing. the factory fuel injected models had a hall sensor on the cam, so im going to try and find those pieces somewhere and see if i can make it fit.. i guess I spoke too soon.

Just before you chuck in the towel, you haven't got some metal filings/crud on the sensor, because a whisker of metal will do that or vibration and air gap closing up or opening?
It also pays to stand back and revisit when you are not so emotive, as I've been in the same boat.

Couldnt see any problems with metal shavings, but I didn't look very hard.. VR sensors are gone for good. I was trying to figure out a way to fit some hall sensors on a cam wheel, but didnt see any of factory FI stuff for a reasonable price, Im reading about salvaging encoders from serial ball mice, Im going to try to use that and have an optical trigger cam wheel.

I havent been able to see anywhere... Does anyone know what the threshold for a digital signal is on the optoin+ ??
the hall sensors I was playing with was .9 volts High , 20 millivolts low. Im not sure what kind of optical circuit output I will get, as Im not very good with circuits, will just be borrowing a design off the web..

I finally got this going. The solution took a lot of thought and trial/error experimenting. Here is what I did.
This bike has external cam belts, and the main pulley had 2 tapped holes. I bolted on a piece of thick feeler gauge cut down to form a single tooth, and fit a hall sensor to sense it.

I didn't have room or patience to fit 2 sensors, so I jumpered optoin and vr2in, basically dual spark off of a single trigger. Then adjusted offset for output 2 to simulate a physically offset sensor.

I ended up using a 5k 12v pullup on the optoin wire, which gave me 12v high and 21mv low, but when connected to microsquirt that dropped to 2v high, which was causing some erratic cranking rpms.. another 5k in parallel got me 4.9v high. I will probably end up using a 1k resistor. (I think that was recommended somewhere in the docs)

Years of messing with getting the VR sensors to work, But only 3 weeks to get the hall sensor working..
Glad im finally done.