MS + Injector wiring
 

DEAR SIRS,

Assuming I wire my injectors for 1+4 and 2+3, does it matter what bank I wire the injectors to when running a MS2?

Thank you very much.

you have a 94 correct?

INJ1 - Y, Z
INJ2 - U, V

91, Brainy, 91. Same as you bro. ---- it, time to ditch the fancy sigs.

then:

INJ1 - U
INJ2 - V

Awesome, much <3 bro, thanks.

FINAL QUESTION, Brainy, for ONE MEEELLLEEEON dollars...

If I wire 1+4 and 2+3, I just drop them in and go, right? I don't even need to adjust my msq?

/This is what the MS forums said, but I'm scared as hell of breaking something on this new engine.

did you make a new injector harness or something?

INJ1 - U - 1&3
INJ2 - V - 2&4

why are you changing the pairing from stock?

Yes, I'm making a new injector harness Brainy.

The only reason why I want to change the pairing from stock is because I "grok" 1+4 and 2+3, as soon as you throw this 1+3 and 2+4 monkey business on me, I get confused.

just do it that way and dont think about it. but it makes complete sense when you consider the firing order of 1-3-4-2 and the wasted spark.

but give me a second to review diagrams and ill tell you.

You just succeeded in confusing the absolute focking hell out of me, Brainy.

From what I understand, with the MS settings I have and how I understand they work, it injects INJ1, INJ2, INJ1, INJ2 each injection sequence.

SPA FUE
1+4 1+3 (Firing 1)
2+3 2+4 (Firing 3)
1+4 1+3 (Firing 4)
2+3 2+4 (Firing 2)

I don't completely grok how this works yet, i.e. on the third iteration, it injected fuel the previous injection phase.

honestly, im not sure it will work how you want.


you should either pair 3&4 and 1&2 or 3&1 and 2&4



too hard to explain. n/m

I'm just wiring it to stock specs now, Brainy, no worries. But I'd like to understand how it works better, I'm missing something very obvious here.

Mebbe this helps:

On a standard 4-cylinder the cylinders #1 & #4 and #2 & #3 move together. So whenever #1 is in TDC, #4 is in TDC. BUT they don't ignite at the same time. When #1 fires, #4 is just pushing out exhaust gas and vice versa. So you can run them off the same coil and spark them in parallel. When #1 needs fire, #4 fires too, but that spark is wasted, because there is no combustible mixture in the cylinder.
Same goes for #2 and #3 - they move together and can be sparked together.

Wasted spark is pretty smart if I understand properly, because the cylinder that doesn't actually need the spark uses almost zero spark energy and the one that needs it gets most of the energy. This is why even heavily boosted high performance 8-cylinders get away with only 4 coils. So all any of our Miatas with less than say 600hp should aver need is two coils.

But I may be wrong as usual.

runs much better in seq fuel/spark

I agree on the sequential fuel. You don't want your fuel to hang out in the inlet area too long. But for spark you can get away with wasted config without loss.

absolutely. but when i switched, there was much improvement.