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

Hey everyone,

I'm working on getting a Yamaha Phazer engine Microsquirted. It's a twin cylinder 500 cc four stroke engine. I've got all the sensors wired and am getting reasonable readings. I did a test with the fuel injectors and they are working as well.

My problem comes from my ignition wiring. I do not understand what the manual is saying. I've read contradicting things from two different spots in the manual, dealing with the"IGN" coax wire, coming from Pin 32 and 33.

The engine has what I've figured is a VR sensor on the crank with a M-0 toothed wheel. The cam position sensor is what I figured to be a Hall sensor.

The way I have it wired (and I hope I haven't wrecked anything aready) is as follows:

The two wires coming from my VR sensor are connected directly to the "IGN" wire. The negative wire is connected to the outside "shield" of the coax wire, and the positive wire off the VR sensor is connected to the inside core of the coax wire.

I've got the Cam Position sensor, which I've figured to be a Hall sensor, wired as follows:

VRIN2+ (Pin 4) is connected to the signal wire
Switched 12V power is connected to the postive wire of the sensor
Ground is attached to the outside "shield" of the coax wire (Pin 33)

Now, I've got this wired cranked, and got nothing for spark. When it's cranking, if it's wired properly, I should see some engine RPM, even if the ignition settings aren't correct in MegaTune, right?

Is this setup COMPLETELY backwards?

Little confused...

Thanks,

Kyle

Kyle,

A VR sensor doesn't really have a negative wire and a positive wire (in the sense that a battery does), though some manufacturers call them + and -, only because that's what people expect to see in 'normal' maintenance situations. Instead, the signal comes out on both wires. If you swap the wires around, you turn the signal 'upside down' (invert it).

MegaSquirt only cares about the zero-crossing, and only one of these. You need to get the zero-crossing going the right way, and you need to set the input capture appropriately. If you get things backwards, you *might* get no tach signal (though normally you would still get a signal, possibly jumpy). There's much more on this here: http://www.megamanual.com/ms2/pickups.htm#vr

Some people have apparently had tach problems with MicroSquirt and solved them with a 10K Ohm resistor in line with the VR sensor lead, so you might try that (since it is very easy).

Lance.

Thanks Lance, I'll try that.

One thing I'm confused about though, is should the "negative" wire from each of the two sensors be connected to the shield of the coax?

And as I've got it setup, my VR sensor on the crank is my input 1, and the hall on the cam is my input 2. Is this correct, or should I switch this around?