Squirts per cycle and injector settings question

[KW78]

Hi all,

I am setting up a new install MS3x (DIYauto assembled) in a naturally aspirated Miata (An NA NA ) 1.6.

I have comm with the laptop last night, and I am working thru all the settings.

I have done a 36-2 crank trigger, NO cam trigger. Wired it for COP wasted spark, and semi-sequential FI. Speed density.

As I understand it now, semi sequential is "batch firing" with the ability to time the pulses and trim the 2 banks, which is what I would like.

I guess I don't understand the squirts per cycle parameter, or its effects. Common sense seems to indicate each injector will squirt twice per cycle, as semi sequential has 2 injectors firing at the same time. I am assuming by engine "Cycle" that means 2 revolutions for a 4 cycle/4 stroke motor. Also, injector staging seems like it should be alternating, because semi sequential seems like it would be defeated with all injectors firing simultaneously.

But, entering 2 squirts per cycle gives me a MS error message saying "invalid combination of semi-sequential and number of squirts/ alternating" upon a powercycle to save the changes. Entering an ODD (1 or 3 squirts ) number gives me a message in tuner studio that it needs to be an integer based setting (makes sense), so the only setting that it accepts is 4 squirts per cycle, which doesn't seem right.

The manual had no specific settings for this configuration.

Reading the forums, I see people have used "trial and error" getting thru this issue, but have to play with required fuel setting, and injector dead time settings.

What am I missing?

Thanks,
Kyle
SPR

[KW78]

I found some information here ( http://jbperf.com/sequential/index.html) referencing MS2 injection code.

The chart here indeed shows a non-cam sensor 4 cylinder setup with staged (timed?) injection is 4 injectors, 2 squirts per cycle (720 degrees crank rot) as I would expect.

The MS3x will not accept this setting.

Any ideas anyone?

Thanks!
Kyle

[slow_hemi6]

Semi sequential with 2 banks will only work with the same number of squirts/cycle as the number of cylinders you have. It is a code mod on the sequential code which as you can expect fires an injector for every cylinder per cycle. This squirt/cylinder is the limitation. If you think that 4 is a pain, try using it on a V8 with staged injection.
When looking at Jeans table you are getting Injector Staging confused with Staged Injection. The chart shows No Staged Injection Vs Staged injection. When using Staged injection a 2 bank system must work as simultaneous so effectively you have a 1 bank system with second switchable simultaneous bank. This results in the only possible combination for a 2 bank, staged injection, 4 cylinder being 4 squirts simultaneous (AAAA). Same 2 bank, 4cylinder engine with no staged injection means that it will fire each bank twice per cycle to give a total of 4 squirts/cycle (ABAB).

[KW78]

. Same 2 bank, 4cylinder engine with no staged injection means that it will fire each bank twice per cycle to give a total of 4 squirts/cycle (ABAB).

So in semi-sequential mode only, the 4 squirts per cycle "setting" has slightly different logical meaning than batch or sequential, because the code mod is essentially acting like it is running a 2 cylinder full sequential with "staged" injectors - the first injector firing per timing table, and the second injector stage firing 360 crank degrees later.... the second injector just happens to be pointing at the companion cylinder set... Is that a reasonable summary??

Well if that setting works that is fine. I just didn't want to have double the expected injector firings going on with a single cylinder. The "batch fire" injector times for the application should be a pretty good guide for fuel delivery as well.

I will scope all that with a labscope when it is running and verify its working as expected. Thanks for helping me understand the differences.

Its almost making zoom zoom noises tonight....

Kyle
SPR

[slow_hemi6]

So 4 cylinder, non staged, two injector channels. On an individual cylinder basis each cylinder will be squirted twice with a 360 degree separation. So in effect, you time the first pulse and the second just occurs 360 degrees after that. Still onto a closed inlet valve at idle/lower speed operation. When this second pulse occurs, the companion cylinder for that injector driver will be at the same timing as the first cylinder was for its initial pulse, but for it's respective cycle it will be the first pulse.
So injections occur every 180 degrees in an alternating fashion and every cylinder gets fueled twice with a 360 degree separation of those pulses.

[KW78]

So 4 cylinder, non staged, two injector channels. On an individual cylinder basis each cylinder will be squirted twice with a 360 degree separation. So in effect, you time the first pulse and the second just occurs 360 degrees after that.

Yes So, from an individual cylinder point of view, it is squirted at twice per 720 degree cycle, which is why I was stuck on that setting...

Thanks!
Kyle