VR sensors on Ducati L-twin

alan_3301 · Post by **alan_3301** » Sun Jan 20, 2008 8:20 am

Hi, I'm installing a microsquirt on my ducati monster, previously carb'd.

It has 2 VR Sensors spaced 90 deg apart, and 1 raised "lump" (about 1" long) on the flywheel which passes under the sensors.

So.. At TDC, the lump has just passed the trigger for the Horizontal cylinder, then...
270* rotation, and the lump has just passed the trig for the vert cylinder,
90* rotation, and it's back where it started.

I'm trying to get away without a cam sensor, and I plan on running injection only for the time being, but i'd like MS to determine the engine position from the sensors, and not from the stock ignition modules.

My questions:

Do I run dual tach inputs mode with horiz pickup+ on VRIN1+, vert pickup+ on VRIN2+, with both pickups - going to VRIN1-?

Because the trigger is when the lump has just passed, I have falling edge ignition input capture, which should be set to rising edge because the manual said it is reversed for microsquirt?

What is "Offset (advance) for Output #2:" for.. No info in manual.

I have many more questions, but I will hold on to them for now..
Thanks in advance.

alan_3301 · Post by **alan_3301** » Sun Jan 20, 2008 11:46 am

Ok, I hooked up the sensor for the horizontal cylinder to vrin1+ and -.
Depending on my settings in megatune, i get anywhere from 1700 to 22500 rpms while cranking, and the number jumps around a lot.

So, I hooked up the sensor to optoin+ and "option" I'm assuming thats supposed to be "optoin-". Now, I get a pretty consistent readout of 350rpms while cranking (no spark plugs installed).

Now what do I hook the vertical cylinder sensor to? VRIN2+ and OPTOIN-?

Matt Cramer · Post by **Matt Cramer** » Mon Jan 21, 2008 7:51 am

For fuel only, I wouldn't bother with the second sensor.

alan_3301 · Post by **alan_3301** » Mon Jan 21, 2008 9:59 am

It seems that I am limited to wasted spark and batch injection, even when only controlling 2 cylinders. Is this correct? Without a cam sensor that is.

also, why would using only 1 crank sensor instead of 2, make a difference for spark control, but not for fuel?

Matt Cramer · Post by **Matt Cramer** » Tue Jan 22, 2008 5:56 am

alan_3301 wrote:It seems that I am limited to wasted spark and batch injection, even when only controlling 2 cylinders. Is this correct? Without a cam sensor that is.

Correct. With no cam sensor, you can tell if a cylinder is at TDC, but it's impossible to tell if it is on the exhaust or compression stroke.

also, why would using only 1 crank sensor instead of 2, make a difference for spark control, but not for fuel?

The fuel isn't really timed to anything so it doesn't need precise timing. Ignition would need to use the dual spark setup for "independent dual ignition" mode, as described in the manual:

Independent dual ignition: alternating tach pulses offset in phase are fed into the two ignition inputs and they produce two ignition outputs to separate coils. This can be odd or even fire - it doesn't matter because the pairs of input/outputs are independent. This would typically be used for a two cylinder motor. In this mode there can be No toothed wheel, No trigger return, and No EDIS. Also set the ignition ISR time mask=0, and the percent mask must be less than the smallest phase offset of the inputs. For example with an even fire engine the phase offset would be 50% so you would want to set the percent mask to no more than 30% to allow for accel/ decel.