# Megasquirt injector harness wiring and req fuel staging question



## LooseNut (Nov 27, 2001)

Hi guys. I posted this at msefi forums but answers are always a little slow there. Please see my question below:

I've got MS2 V3.0 intalled on my 1990 VW with the 1.8L supercharged 4 cylinder. I plan on making an attempt to start this weekend. Now that I'm setting the parameters I see that I may have made a mistake with the injector wire harness. I've got it built like the generic schematic says to.
I took the injector numbering literally so 32,33 bank is wired to squirt cylinders 1 and 2. 34,35 bank is wired to squirt cylinders 3 and 4. 
So now I read that my injector staging should be 2 squirts/alternating. But if I'm sparking in the order of 1 - 3 - 4 - 2, it seems that cylinders 3 and 2 wouldn't have fuel when they need it! It looks like I'm forced to stage it as 2 squirts/simultaneous until I re-build the injector harness. What I need is injectors 1 & 3 on one bank and injectors 2 & 4 on the other bank? 
FWIW, stock form had all injectors wired in parallel so it must have been 2 squirts/simultaneous. This engine prefers a somewhat high idle most likely due to the supercharger drag. It's simply smoother and more stable when above 850 rpm. A lot of people blame the cold start valve to be leaky (boost leak) so they ditch it and set the idle with the adjustment screw and leave it at about 900 rpm idle. Also, I'm using the original injectors which are high impedance.
Thanks for the help! Hopefully I'll be driving by next month! Can't wait.


_Modified by LooseNut at 11:33 AM 5-29-2008_


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt injector harness wiring and req fuel staging question (LooseNut)*

For a 4cyl they 'should' be wired 1/4 and 2/3 with the VW firing order. That being said it really only can make a difference at idle and you probably won't be able to tell the running difference between the two. It's batch fire injection, not timed in any way to valve events, once the rpm goes up, it *really* doesn't matter!
I usually run 2/alt, though I've run 2/simult before with a single bank (just inj_1 wired to all 4 like a stock Digi car) with double req_fuel. Still works fine.
Hope that helps.


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## LooseNut (Nov 27, 2001)

*Re: Megasquirt injector harness wiring and req fuel staging question (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_For a 4cyl they 'should' be wired 1/4 and 2/3 with the VW firing order. That being said it really only can make a difference at idle and you probably won't be able to tell the running difference between the two. It's batch fire injection, not timed in any way to valve events, once the rpm goes up, it *really* doesn't matter!
I usually run 2/alt, though I've run 2/simult before with a single bank (just inj_1 wired to all 4 like a stock Digi car) with double req_fuel. Still works fine.
Hope that helps.

Yeah, that does help. Thanks. I think I may just be paranoid about where the fuel is and how to make it most efficient. I'm guessing premium will be at $5 a gallon before the summer's over.


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt injector harness wiring and req fuel staging question (LooseNut)*

There's a chance it might be slightly better 1/4 and 2/3 for efficiency and trying to run way-lean (16-17:1). Can't be sure until you try though.


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## alec stensaa (Jan 10, 2008)

*Re: Megasquirt injector harness wiring and req fuel staging question (need_a_VR6)*

i could be wrong and sorry if i am but i would dubble check that because i think it is like this will show you. 1/3 2/4


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt injector harness wiring and req fuel staging question (alec stensaa)*

That diagram makes me want to puke a little, can you stop posting it?







MS's running a cam sensor and MS2 with semi-seq would use 1/4 and 2/3 pairs.


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## radics1 (Jul 31, 2008)

*Re: Megasquirt injector harness wiring and req fuel staging question (need_a_VR6)*

I use 1-3 and 2-4 according to someone here in Vortex.Car runs fine,i didnt know if it would make any difference if i change it to 1-4 and 2-3,i may try it.


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