"Single Tooth" trigger on one cylinder

[bpsims]

Just got a Microsquirt V3 and wondering if my stock ignition pickup will work.

250cc Honda Helix scooter motor - This is what I'm working with:




I've tried a number of ignition settings in Tunerstudio but can't get an RPM tach signal.

The 2 wire VR sensor is hooked up to VRIN1+/VRIN-. IGNITION OUTPUT #1 goes to a CDI to drive the coil.

I understand that this isn't the best way to control ignition and have started looking for trigger wheels but I'm asking if a trigger setup like this will work with Microsquirt and what the settings are to get an RPM signal.

Thanks!

[Matt Cramer]

That should work if you do not enable dual spark or a wheel decoder.

[dontz125]

That tooth might be JUST long enough to cause problems. Try it and see - set "Number of Teeth" to zero (silly as it sounds).

[bpsims]

Thanks for the feedback. I spent way too long on this over the weekend and never got much success. At one point, I was able to get some erratic sparks out of the spark plug but then no more. I was also able to get the RPM tach gauge to respond but it was bouncing around like crazy. It would hit 8000 RPM while cranking and then drop to 0 and then back up again.

I hooked the VR sensor up to an oscilloscope and grabbed this with my phone:


And then stumbled on this:
)(http://www.megamanual.com/ms2/36-1.htm)

I'm thinking the width of my "tooth" is just too long and it's causing problems like dontz125 mentioned.

I'm about ready to take my grinder to it and shape it to match the VR sensor width. But I'm not sure that will fix the erratic signal that the Microsquirt is seeing. I could understand the timing being off a few degrees based on the image above but not the wild swings I'm seeing.

[dontz125]

Yeah, it's amazing what a few degrees of jitter can do. I have a filter circuit that will work, or - as you say - you can just grind down the tooth. Be sure the tooth edge is nice and square, or you get funny things happening as the revs pick up.

[24c]

As dontz125 says that tooth will give you a few problems, but I'm surprised you cannot register tach or RPM.
Does this scooter have electric start?
How many AC volts is it putting out peak to peak?

As an experiment, try hooking up the scooter to a car battery, whipping the plugs out and see if things improve.

Ideally, I'd try and get another stator, and mod that first. I'd also look at using a Hall effect sensor, as these process the tooth signal to a simple on/off state, and can get round tooth deficiencies.
Also admitting my ignorance here, but does or can a MicroSquirt trigger a CDI coil set up? Never done this myself, so not sure.

[dontz125]

He is registering tach and RPM, but it's fluctuating wildly - this is a single with a long tooth, so the uS doesn't even have the 'other' teeth of a typical UJM 1L3S to help keep things even remotely straight. Mix in the fact that this is a single, with the constantly varying RPM that these are subject to, and I'm not surprised in the least that the uS is utterly baffled.

A Hall sensor would work.

A uS can TRIGGER a CDI in the same way it can trigger an LS2 COP, assuming the CDI in question has a logical trigger input, but it cannot DRIVE a CDI system.

[bpsims]

As dontz125 says that tooth will give you a few problems, but I'm surprised you cannot register tach or RPM.
Does this scooter have electric start?

It's actually a mini buggy using a scooter engine. It does have electric start. A little more tinkering and I can get a solid reading of around 800 RPMs for a few spins and then the tach jumps up and down, turning red and generally freaking out. I'm cranking w/o the spark plug, so I'm thinking it's correct during the brief time I see 800 RPM.

How many AC volts is it putting out peak to peak?

I'm not entirely sure, I wasn't paying a great deal of attention. I had just picked up the oscilloscope from a surplus shop and know just enough to get a pretty graph on the screen. It's fairly small - in the millivolts I believe.

As an experiment, try hooking up the scooter to a car battery, whipping the plugs out and see if things improve.

Ideally, I'd try and get another stator, and mod that first. I'd also look at using a Hall effect sensor, as these process the tooth signal to a simple on/off state, and can get round tooth deficiencies.
Also admitting my ignorance here, but does or can a MicroSquirt trigger a CDI coil set up? Never done this myself, so not sure.

I do have some Hall effect sensors laying around that I'll play with when I open the case up to expose the flywheel with the BIG tooth on it that I plan on grinding down. Ultimately, I'd like to do this right and use a multi tooth trigger wheel on the crank and put a sensor on the cam as well. But everything else is hooked up and working fine - I just want to hear it fire up after all that wire splicing!

A little more information: The buggy had a previous FI kit installed on it that I wasn't happy with. The web site is down but, if you're curious, this link has some information on it: http://mastercircuits.blogspot.com/2010 ... n-kit.html. The kit came with a "special" DC CDI that replaced the original AC CDI that the buggy had. This new CDI was fed a signal from the ECU as opposed to the old AC CDI that was triggered directly from the VE sensor on the buggy. I'm assuming the ECU was giving the new CDI a logic level input like the MicroSquirt but I can't get a response from the seller to confirm. It was also able to control timing. So, I'm thinking it had it's own custom code to deal with this type of VE sensor signal.

[bpsims]

He is registering tach and RPM, but it's fluctuating wildly - this is a single with a long tooth, so the uS doesn't even have the 'other' teeth of a typical UJM 1L3S to help keep things even remotely straight. Mix in the fact that this is a single, with the constantly varying RPM that these are subject to, and I'm not surprised in the least that the uS is utterly baffled.

A Hall sensor would work.

A uS can TRIGGER a CDI in the same way it can trigger an LS2 COP, assuming the CDI in question has a logical trigger input, but it cannot DRIVE a CDI system.

Yeah, I'm trying to track down how exactly this CDI is triggered. I'm assuming it takes a logic level input (~5 volts) but I'm not sure. One more thing to test out.

[Patrickmccaherty]

Have you figured this issue out? I have the same setup and would love any information.thank you