Semi-sequential fuel injection on M20 w/MS2

[shanehutton]

I just got my car running and have a pretty stable idle but we were making semi educated guesses along the way.
It's a MS2 with an additional injector driver board:
http://www.jbperf.com/quad_ign_inj/index.html
We are using 3 of those drivers and have paired the injectors up 1-6, 2-5, 3-4.

I can't find anybody who has used 3 banks on a 6cyl so I am a little lost as to how to configure everything and make sure I haven't screwed anything up.

Does anyone know the injector dead time for the stock m20B25 injectors?

Here are the settings I have right now:

[DmcL]

i can tell you dead time for stock injectors straight from a stock ECU but its a raw value number as i dont know the conversion to ms. well i do know a conversion but its not verified so..

stock dead time map is 1x4 and is tabbed 800rpm 2000rpm 3000rpm and 4000rpm and have a raw value of 200 for all 4 cells (range of raw values is 0-255).

via the unverified conversion im showing 29.30, 11.72, 7.81 and 5.86 but no garauntee whether thats right or not.

[shanehutton]

The numbers I am seeing floating around for other injectors are around 0.6 - 1.0ms.

[nando]

they are older injectors, probably about 1.2-1.3ms. 1.2ms is a good place to start, it will work fine. You should be well above the non-linear zone of the injector response using stock injectors anyway.

pair the injectors 1&6, 5&3, 2&4

injector dead time is measured against voltage, not RPM (though sometimes it can be both, voltage is always one of the axis's). I don't think the table DMCL found is really a dead time measurement; 30ms is not even close to being a reasonable value.

[shanehutton]

I paired them based on firing order as the ones I used are 360deg from each other so with 2 squirts it would fire at the same time for each cyl. Why are you suggesting 1&6, 5&3, 2&4? I didn't think through any other options so I would love to know the reasoning / benefit?
I found it odd that I had to use injector staging : Simultaneous as my first guess was alternating but that sent the req fuel way too high.
As it stands, based on these settings above, I am just working on blind faith that the MS knows I am using 3 banks of two and is doing what I need it to do. I am going to oscilloscope the injectors to make sure that they are actually shooting 2 squirts per cyl and not just batch firing the entire 6 at once. It idles ok though so I know that all 6 are getting fuel which is a good start.

[nando]

sorry, I meant 1&5, 6&2, 3&4

so that the angle would be close to each other (only 60* apart)

I don't know that it's worth doing multiple squirts per cylinder, but you can play with it and see what results you get. usually the response time has a significant impact on the overall duration and you can't really do multiple squirts without bad side effects.

[shanehutton]

So you are thinking 1 squirt per bank of 2 cylinders just before the intake stroke on the earlier of the two?
So 3 injections total for each 720 degrees of crank rotation?

I was thinking 2 squirts per bank of opposing cylinders just before intake on each so one would sit and then the second would come just before intake. Come to think of it, without a cam sensor the MS doesn't know if TDC on #1 is intake or exhaust so I think I have to do 2 squirts or else I could be injecting 100% of the fuel 360 degrees from where I wanted to.

What I don't get is how does the MS know what cylinders I have paired up and when to fire each one? I would have assumed I could tell it which driver to fire based on TDC #1 and then specify when to fire driver2 and driver3 based on degrees off TDC #1 but I can't find anywhere to tell it that.

I am pretty lost. I am thinking about replacing the injectors for M50 or 19# ones anyway so I guess I could re-wire the injector harness while I am in there.

[nando]

yeah. Under most conditions you want to inject into a closed valve. you may consider using a map rather than fixed timing, if it's possible with semi-sequential. idle can require different timing than part and full load.

[shanehutton]

Any idea how MS knows what driver to fire? I can't find anything where I can tell it what cylinders I have on each driver.

[nando]

it's hard coded. Channel A - B - C is the firing order. Works the same as wasted spark.

[shanehutton]

OK. At least I got that right. Now it is just to confirm that I actually have 3 banks firing at separate times.

[zaq123]

sorry, I meant 1&5, 6&2, 3&4

so that the angle would be close to each other (only 60* apart)

I don't know that it's worth doing multiple squirts per cylinder, but you can play with it and see what results you get. usually the response time has a significant impact on the overall duration and you can't really do multiple squirts without bad side effects.

Old post but are you sure that the first pairing combo was incorrect? For example Haltech as well as MS recommends 1-6, 5-3, 2-4 pairing

https://support.haltech.com/portal/en/kb/articles/fuel