Need some help with this Vtwin....please!!!

[800vtwin]

You want a cylinder offset of 90, not -270. Since #2 from the uS automatically fires 360* after #1, a setting -270 is firing #2 at 630* after #1. You want it to advance 90*. Most vtwins will fire the 2nd cylinder this way. No matter which way you look at it- your TDC's are 90* apart. And this will need a setting od +90 or -90. But i'm pretty sure you will need it at +90.

trigger offset needs to be a negative number. Not cylinder offset.

If you have NO cam sensor - What is telling the uS to fire on the compression stroke instead of the exhaust? It could fire right one time you crank it but be firing 360* off the next time. = you need a timing reference. You need to add a cam sensor. Or switch to wasted spark. = change your skip teeth to 0.

Also since you have 13 delay teeth, make sure the trigger offset is 0 or -5. You could change delay teeth to 0 and trigger offset to -135.

Yes use calculated for crank trigger. It probably won't start (or be very very hard to get started) with trigger rise or fall, the timing will be all over the place.

[tech3sandcars]

Thanks, first of all let me say I had ign #1 and #2 wires backwards, I fixed that and here is where I stand. I did set the output #2 to 90, I am set up for wasted spark, calculated is also set, i did do the delay teeth to 0 and trigger offset at -135, that worked the same as skip teeth 13 with 0 trigger offset.

I have actually tried code 2.89, 3.110, and 3.43 all with the same results. I got the configuration to work when I was cranking with the timing light. Set the timing table to 0's and used the trigger offset to dial in a few -degrees to agree with the timing light for both the front cylinder and the back clyinder. Went back to a normal timing table and the engine would fire and sometimes run on the back cylinder and sometimes on the front cylinder. My timing light showed that things were kinda jumping all over the place, and it looked like the tach was running about half of what it should be. Played with filter setting with mixed results, tried a few other thing with no luck of a smooth running engine. Whats interesting is the triggering into the system looked fine, the tach signal was smooth (although it looked half speed as mentioned earlier), the advance guage looked good, but just didn't run good.

I decided to scrap the ignition side of the uS and put back in the stock ignition box and feed the tach signal into a fuel only uS, it ran like a champ. other than fuel tuning it rev pretty good like my other engine runs.

Don't know where to go from here but had to abandon the ignition side of the system cause our race is coming up in 2 weeks.

Here is the lates msg.

2010-03-24pm.msq

(25.09 KiB) Downloaded 57 times

[800vtwin]

2 things.

Injection control - you want 2 injection per cycle. (cuz you have 2 cylinders) You have it set to 1.

You do not have wasted spark set. Skip teeth is at 24- should be 0.

Without wasted spark- and you have no reference spark output vs stroke position. (reason it fires on one cylinder, than the other)

I don't have the beta code ini loaded to my puter so i cannot view your tables- but have you checked your cdi curve and entered that for your timing table? I would guess 12-16* for base timing at idle?

The microsquirt ignition is very solid. It just needs set right per application. You can also check the VR polarity. Just switch to rasing edge and if it works = you're backwards. Swap the polarity than switch back to falling edge.

[old guy]

800 vtwin

I don't understand why you are telling him to set the skip teeth to zero ?
As per the Megamanual

Skip Teeth: Skip tooth is the number of teeth between "tach" triggers. (It is the number of teeth skipped after the last tach signal before MS-II calls a tooth a tach signal.) What you need to have happen is for MegaSquirt-II to 'skip' a certain number of teeth so the only the right number of teeth are counted as 'tach signals' per revolution. In general, this is:

4-strokes: skip_teeth = (2 × M) / #cylinders
2-strokes: skip_teeth = (M) / #cylinders

Some permissible combinations are:
Skip Teeth Setting
Wheel 12-1 24-2 36-1 60-2
cylinders
(4-stroke)
2 12 24 36 60
4 6 12 18 30
6 4 8 12 20
8 3 6 9 15
10 n/a n/a n/a 12
12 2 4 6 10

If he wants it to fire wasted spark he should set skip teeth to 12 and the second ignition output to 90 deg.
As his 13th tooth is top dead center I would set the delay teeth to 14 then set the trigger delay to -15 (360/4=15) and that would make it fire on the 13th tooth.
I used these setting on a Suzuki Sv1000 which also uses a 24-2 wheel and it worked fine on my test stand.

For some reason the table I c&p from the Megamanual doesn't come out right but if you can't figure it out, check on the Microsquirt info page under toothed wheel config.

[tech3sandcars]

Thanks for everyones replies, I really appreciate it. Yes I do want wasted spark, which should be easy to define but thats where I am struggling, I do not have a cam sensor nor would it be easy to mount one. Just a little review, I have a 24-2 wheel and the cylinders are 90deg apart, and I want wasted spark. Sounds like you have done this configuration on the bench, I am just no grasping why one cylinder was running and one not, when I had the cylinder #2 set at 90deg. I think if I read your comment correct my skip teeth of 24 (vs 12) could have caused my rpm guage to be reading half but also shouldn't it have been running on both cylinders just not firing every compression stroke rather every other one?? The skip teeth of 12 does make sense, but reading the microsquirt info page about triggering I didn't catch that anywhere., but definitely makes sense cause my tach always seemed to be running half speed. Are we pretty solid on the thought of skip teeth to be 12?

[24c]

Are we pretty solid on the thought of skip teeth to be 12?

This would give two tach events per crank revolution, which would mean wasted spark, and with the right offset it should make a wasted spark for the second cylinder, which is what you want. So if oldguy has got this to work, I'd try his settings, and at least you can make progress.

However, IIRC, it should be possible to spark your V twin engine with one tach event per crank revolution, and apply an offset to IGN2 for your second cylinder, which is where 800vtwin is coming from, and I don't understand why it is not working for you.

[800vtwin]

12 skip teeth is a correct setting. And will work for sure.

I was playing with this over a year ago when i did an install and am thinking this is how it code worked. The code would not allow every tooth to be a tach tooth and defaulted to 1st tooth after missing. And you would get a tach every 360*. (= wasted spark) And the reason I did this was because it takes processing power to sit and count teeth while waiting to set up spark. And why add more info and lines for the ecm to calculate? Using less processing is better. - but i could be remembering wrong??? (i don't have a bench setup and can't get to test this right now)

If 0 doesn't work/ does spark every tooth- I apologize and 12 is the only setting.

The cylinder offset for #2 is always #1 +360* + advance. And in this case, will always be 90* no matter what the skip teeth are.

Change injection events to 2 and see if that fixes your 1/2 rpm.

[tech3sandcars]

The trigger wheel is mounted on the crank so thats 24 teeth per crank revolution, so during a full 4 cycle period of 48 teeth (2 revolutions) wouldn't I get 2 ignition events if skip teeth is 24? Since wasted spark fires every revolution of the crank, i'm still quite not getting the skip teeth of 12, I can't get away from the thought that 12 would give me 4 ignition event during one engine cycle. My brain tells me that the skip teeth is 24 and its what produces the tach pulse, and one tach pulse per revoltion is what I am after ( i think)??? I'm not saying my 24 is right, I don't think it is cause it didn't run, but just want to understand how uS is thinking. On the Microsquirt info page they talk about all the scenario's except for this one, which I think would be pretty popular since there is lots of Vtwins out there with no can sensors. I am going to make this work sooner or later since theres a whole pile of guys on a couple other forums that are anxious to try this.

Its hard to deal with the flywheel on this motor, the trigger teeth are on the flywheel and you only get this 1" round viewing hole, plus its in oil so the only time it is viewable is when your cranking otherwise theres oil everywhere.

I'm good on the cylinder offset of 90.

Also does injections per cycle effect RPM value, I thought injections per cycle just had to do with how many times the injectors wiil fire per tach pulse?

[old guy]

Look at it this way. If you set skip teeth to 12 you will get a spark at TDC and another 180 deg later each revolution of the crank. Set the second ignition delay to 90 and you get 180+90 = 270 which is where you want the rear cylinder to spark. It will do this each revolution and you have wasted spark.
You also need to understand that if you want it to fire on the 13th tooth, set the delay teeth to 13 which will fire it on the 14th tool and then put -15 in trigger offset to move it 1 tooth to back to 13. If you don't do this you will not be able to retard the timing when you are fine tuning it with the trigger wizard.
I have a test stand that I can drive a trigger wheel with a variable speed electric motor and I know this configuration works with a Suzuki SV 1000 ignition which is also a 90 deg v twin with a 24-2 wheel.

[tech3sandcars]

Thanks Old Guy, it helps when things can be explained in different ways, that explanation makes good sense to me. I just didn't pick that up anywhere in any manual. Can you see from my last msq or explanation why i was firing on one cylinder?? sometimes front or sometimes back cylinder?, that part still confuses me a little. Like I said earlier its really hard to test bench my set-up but after all this I certainly may do that.