New instal, injector wiring / timing question -

[KW78]

Hi,

I am doing a new build of a NA miata 1.6 with a Ms3x. It races in a limited prep class in NASA.

I am only using a 36-2 wheel on the crank, no cam sensor. I intend to have wasted COP, and either batch fired or semi sequential injection mode. As such, I am wiring the injectors using pins 32-35, on the MS3 board and not using injector outputs from the MS3x board.

I have read many threads here and elsewhere and the manuals. I still don't understand the fundamental theory difference between the two injector modes. I have read lots of posts where people are guessing and using trial and error for req fuel changes between the two also...

So, now as I went to make the injector connectors, I was intending to make my bank 1 injectors #1 and #4 on the INJ1 wires (pin 32,33) and bank 2 injectors #2 and #3. This mirroring the wasted spark, which, with the injection timing table that seems to reference TDC of the firing stroke, seems intuitively correct.

(Is the injection timing table even used on batch fire? or Semi sequential mode?)

I thought I would refence the factory manual for another point of reference only to discover that they are batch firing #1 and #3, and #2 and #4. This muddles the injection timing theory for me even more.

Can anyone fill in the gaps I seem to be missing here? I would REALLY appreciate thoroughly understanding the theory and intent here.

I realize that either way is going to work probably, but one MAJOR reason we chose the MS3X on this project is for the individual cylinder tuning abilities. Finding a couple horsepower on these limited prep class miatas is worth the effort on the dyno and makes a difference on the track.

Thanks much in advance for any help!!

Kyle W.
Sector Purple Racing.

[jsmcortina]

To benefit from per-cylinder fuel trim you need to use the MS3X injector outputs.

James

[KW78]

To benefit from per-cylinder fuel trim you need to use the MS3X injector outputs.

James

Really? And I just crimped the connectors into the harnes.....

On the MS3x outputs, do I need to enable full sequential to do individual cylinder tuning, or will it respond to trimming a bank for example?

Still would love some discussion on the difference between "Semi"-sequential and Batch.

Thanks,
Kyle

[grom_e30]

semi sequential is a bit like wasted spark but for the injectors they are fired in pairs each rotation of the crank but timed to a specific angle, where as batch fire is not tied to a specific crank angle the injection timing can change from one start to the next.

[KW78]

semi sequential is a bit like wasted spark but for the injectors they are fired in pairs each rotation of the crank but timed to a specific angle....

THANKS!!

I have loaded an older ms3x project and played around in TSu. It look like semi sequential turns on the injector timing table, so sounds like I can mess with that. This motor is going to operate 5500-8000 for extended times, so it seems like you should allow more time for the process to work the higher the RPM, but maybe it doesn't matter if you just have enough time with a big setting in all conditions.

Also from within tunerstudio, it looks like there are INJ1 and INJ2 channels present in both the fuel trim table list, and the EGO sensor mapping dialogue. The trim table has a 6x6 table active implying that is available, with the "Sequential fuel outputs" set to STD fuel. and set to SEMI SEQUENTIAL.

The CYL 1 thru 4 trim tables never are active unless fuel is set to FULL SEQUENTIAL and the output is set to MS3X. Interestingly, if set to MS3X outputs, no trim tables are active in any mode but FULL sequential.

Thanks again!
Kyle

[grom_e30]

with semi sequential and full sequential the main advantage of the injector timing is found at idle and low rpm. at high rpm the timing has less effect as the p/w is much larger.