Sequenced batch fire?

[nathanhardy]

I have a vr6 turbo wondering if this would be worth trying out! Has anyone got experience with it, basically I need to know if I leave it for start tigger and then what would be the spacing for time mask in a 60-2 tigger wheel I'm assuming that's what I'd do Is just devide 6 into 60 so I'd make that 10?

[Rick Finsta]

See my post in the second page of this thread.

Basically just set the trigger to 0 or 1 and then the injector time mask for a six cylinder would be 100=100%=120* and any number between 0-100 would be (X/100)(120) in crank degrees.

I've wanted to verify I "get" this so here is an explanation (I think) on my setup. I run a 36-1 wheel and two alternating injections with a trigger offset of 43* (that is the sensor passes the missing tooth at 43* BTDC, putting it around tooth 5 at TDC). So on my V8, 100=100%=90* between tach pulses (90x8=720 which is one full cam revolution). If I set the Time Mask to 50=50%, that means I will be firing the injectors halfway between tach pulses, which is 45* of crank rotation. If I subtract my trigger offset, this means the injection event will happen 2* ATDC of whatever cylinder coincides with Trigger 0 or 1.

I think the 0 or 1 just changes which bank you are referencing for your tach pulse, so in my firing order of 1-8-4-3-6-5-7-2 it would either be firing referenced to cylinder #1 or #6, 360 of crank rotation offset. Since I fire twice per 720*, it doesn't matter as the cylinder sets (1-8-4-3 and 6-5-7-2) are analogous as far as fuel distribution goes with my intake manifold.

If I'm wrong then I hope someone can get me a better explanation on this, as I've not been able to wrap my head around if this really works with less injection events than tach pulses per crank revolution...

[nathanhardy]

Way over my head there rick!! lol, math is not my strong suit.., after re reading it again and again I think it's clearing up for me, so my tigger wheel degree is 78* so how do you find the right degree to fire the injectors? Half of 120 is 60 so is that 18* btdc? So if I set it at 50* then it's triggering the injector then? I feel that too soon but I don't know the right timing!

[Rick Finsta]

Honestly I'm just hoping to get someone in here with a better idea to verify I've got it right.

Basically, with a toothed wheel every cylinder has a trigger pulse - my understanding is these basically coincide with teeth on the trigger wheel (which we used to have to enter into Megatune or TS but now it is done automatically with the number of teeth and the trigger offset setting).

With a four stroke engine you have two full crank rotations for every one cam rotation, which means every cylinder fires once. Since one rotation is 360*, then the two crank rotations are 720*. If you divide this by the number of cylinders you have, you get the crank degrees per trigger event, since there is one trigger per cylinder with the toothed wheel. So for a 4 cylinder it is 180* between triggers, for a 6 cylinder it is 120* between triggers, and an 8 cylinder has 90* between triggers. All this does is phase it inside that little time between triggers, and only between a certain set of triggers. So it is NOT firing at the same crank angle for each cylinder (only for the one upon which its trigger event is based), but it should be ALWAYS firing at the same point relative to crank rotation so it is at least consistent.

So it is less about the actual timing and more about consistency, because without it the MS just picks a random trigger event and starts injector pulses off that meaning it could be any of 4, 6, or 8 crank positions depending on the number of cylinders.

So really "don't overthink it" might be the answer here?

[nathanhardy]

So based on my ms settings it already knows im running a 6 cliyder 120* right? Which equals 100% right? So now I need to figure the best % to set. Is there math used to find out when is the best degree to fire them? Correct me if im wrong 78* would be 68% right? Which is tdc? Wouldnt you want them firing before tdc? I under stand the consitant factor of it and that it is primitive but I figure it can get pretty close too if set right

[Rick Finsta]

MS already knows how many degrees between trigger events because it creates the trigger events when the right tooth passes the sensor with a trigger wheel setup. That's how it is calculating things like ignition timing and advance. That might not be an articulate way of putting it...

Generally injection timing is based around intake valve events, so you would need your cam specs to know when to play around with the timing.

HOWEVER.

Since this feature is only changing the timing relative to the valve of one cylinder and not the others, it doesn't really matter. Just set it at 0, then move it 10% up at a time and see if you find a place where the engine likes it.

[nathanhardy]

Sounds like a plan! Thank you! What could be expected with the engine doing this? Rough running/lean, is there anyway to kno when you've got it set the best way by feel or through MLV

[Rick Finsta]

I'd look at things like manifold vacuum and AFR to see if there is somewhere it becomes more efficient, and I'd look around idle and just off idle or at cruise.

I'd like to know if you can use other numbers besides 0 and 1 for the trigger, as on an engine like the Olds V8, the inner and outer cylinders are fed differently, so the timing based on one or the other might help balance things out if I could go at least up to trigger event number 4 or something. I guess I can put numbers in and see if it works...