Base Ignition Settings

[hufferfuely]

I see that the megasquirt v3 main board had trim pots than can be adjusted to eleminate noise in th vr signal. Is this possible with microsquirt?

[24c]

Didn't SQLguy? have issues with his other unused VR sensor on his set up interfering with the wired VR sensor...IIRC, disconnecting it was not enough, I think he pulled it off, but later made a custom toothed wheel.
hufferfuely do a search, I think the topic was called something like "how many teeth etc"

[hufferfuely]

Grippo,

I have the two sensors hooked up now and this is the result on tachref.

tachref.JPG

(63.02 KiB) Not downloaded yet

Looks odd, but the cam signal is nice and consistent. Which dual spark setting should I use? Do I actually need to hook up both ignition out 1 and ignition out 2 to my one coil?

-hufferfuely

[24c]

... Should this be a two tooth setup with no missing teeth or a four tooth setup with two missing teeth? You can only see one of the "teeth on the outside diameter of the flywheel in the picture but there is one on each side.

Just seen this, I think this is two teeth, none missing, as I have 4 teeth none missing and a cam sensor on my engine, and it runs OK. My teeth are a very similar duration to yours. I would use a single crank pick up if you are not doing so at the moment.

PS You can place a 1K resistor across the VR sensor outputs to clean up ripples around the 0 volts point

[grippo]

I have to understand the engine configuration. It is 2-cylinder, 2-stroke and has 2 sensors. One sensor is measuring 2 180 deg apart teeth on the flywheel. I assumed the other sensor was also measuring these same two teeth, it was just located at a different position on the circumference. Since this doesn't appear to be the case, where is this second sensor and what is it measuring ? Is there another tooth not on the flywheel ? Also, do you have a single driver to a dual wasted coil pack or two outputs going to two different coil/ driver packs ?

Do NOT tie the outputs together. There is a lot of information on this if you go to the Dual Spark menu (on the left sidebar at www.microsquirt.info). The last section is new information and the very last configuration covers 2-stroke.

[hufferfuely]

Grippo,

it is a two cylinder two stroke with two vr sensors approx 30 degrees apart. They both measure the same two teeth on the flywheel. Each tooth is 2-1/2" Long and the two of them are 180 degrees apart. The teeth are so long that they can trigger both sensors at the same time. I am using one wasted spark coil to run both plugs. The tooth are on the outside of the flywheel, and the magneto is on the inside of the flywheel.

The point where a tooth is in front of both sensors at once, is approximately 10 degrees BTDC on cylinder one. Then 180 degrees later, the other tooth is in front of both sensors again and #2 is 10 degrees BTDC.

I checked another engine of the same make and model with TachRef and get the same signal. I have elimnated and tested for all sources of noise. Disconnected leads from magneto, powered from seperate source, etc. and I keep getting the same crazy signal i posted ( hree tach signals, one cam signal, two tach signals, one cam signal......)

Hufferfuely

[hufferfuely]

24c,

I tried various resistors across the sensor outputs, but the signal is still not solid. This changes the numer of pulses, making me think there is noise. I can get it to repeat most of the time, but now and then it misses a tooth.

Hufferfuely

[24c]

it is a two cylinder two stroke with two vr sensors approx 30 degrees apart.

OK, you don't need that second sensor. I'm guessing but that two VR sensors are a starting aid or similar, and your original ECU ignores one over a set rpm. Does it have a kick start?

Re the resistors, I just use one 1K across my crank sensor to clean up the ripples, but it does clip the peak to peak voltage...I have a post somewhere http://www.microsquirt.com/viewtopic.ph ... 90#p149190 and if you look at the purple trace, the bottom two on this thread/topic, you can see the effect of the 1K resistor on the flat portion between the peaks.

So back to your engine, disconnect and remove one of the crank sensors, you do not use the VR2 (cam) sensor, as you don't have one
If you have a twin ended 12V coil? if not get one and run wasted spark like most do, assuming it's a parallel or inline twin, not a vee.

[hufferfuely]

Without the resistor I get the tachref I posted previously with three pulses, then two pulses....repeating

with the resistor now I get two pulses, then two pulses....repeating. I think i am getting four pulses every tooth. Therefore thare are basically 8 pulses per revolution and I need to fire on the first and fifth pulses.

How would I set this up in the ignition settings?

[24c]

Therefore thare are basically 8 pulses per revolution and I need to fire on the first and fifth pulses.

I don't know why you are using the second VRsensor, but to answer your question, you have 8 teeth, 0 missing, skip teeth 3, which would give you 2 events per crank rotation. I hope those pulses are equal distances apart. What tooth is being measured with VR2 in TachRef above, yellow plot?

Are your cylinders 180 degrees apart, ie TDC on one BDC on other ?