Blackbird Rush
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| posted on 5/4/09 at 07:04 PM |
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Megasquirt wiring question
Been wiring up today and looking at the megasquirt v.3 wiring diagram it shows the 4 injectors in banks of 2 ( wasted squirt) but there is no cylinder
number related to each injector on the diagram??
Is it batch fired as standard (all injectors fire at the same time) as i can t find any info in the mega manual.....
or are they bank fired 1&2 , and 3&4 ?
Ash.
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paulf
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| posted on 5/4/09 at 07:41 PM |
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It will do either dependent on settings for number of squirts per rev.
Paul
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clairetoo
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| posted on 5/4/09 at 07:42 PM |
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I usually wire up the four injectors 1&3 , 2&4 , then set the megasquirt to fire 2 per cycle , alternating .
They are batch-fired - setting 1 per cycle will fire all four together .
Its cuz I is blond , innit
Claire xx
Will weld for food......
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piddy
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| posted on 5/4/09 at 07:43 PM |
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I wired mine as in this diagram. It works fine set in Simultaneous and Alternating.
 
Rescued attachment 1-wiring_EDIS.jpg
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Blackbird Rush
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| posted on 5/4/09 at 08:22 PM |
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Ta
I'll wire them up 1&3 , 2&4 then and set the rate via the software.......
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BenTyreman
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| posted on 5/4/09 at 09:06 PM |
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I joined injectors 1+4, 2+3 to match valve opening. Setting 4 squirts alternating will ensure absolutely equal fuelling across all cylinders. Other
people recommend 1+3, 2+4. Not sure why. Possibly a better wiring for 2 squirts alternating?
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mark chandler
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| posted on 5/4/09 at 09:58 PM |
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It really makes no difference, the squirts are relative to engine rpm not crank position.
If you look at early EFI systems they all ran batch until emmissions forced them to be a bit more clever, but this only makes things cleaner at idle
and low revs.
Megasquirt 2 x squirts per engine revolution on a 4 stroke engine means that 3 out of 4 squirts hit a closed inlet valve, once the revs build you are
just providing a mist of fuel that get sucked in when the valve opens.
Regards Mark
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BenTyreman
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| posted on 5/4/09 at 11:27 PM |
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I've always been under the impression the it's squirts per cycle not squirts per revolution.
From the MegaManual:
quote:
Injections per Engine Cycle is set the number of squirts you want per engine cycle. You want this to be set so that your idle pulse width is no less
than 2.0 ms, if possible, and your Req_Fuel is less than 12-15 milliseconds, but more than 8 milliseconds. These values allow proper tuning of the
idle mixture while maintaining the ability to apply enrichments (acceleration, warm-up, etc.) under full throttle. This is the total injector
events that you wish to occur for every engine cycle (360 degrees for two stroke engines and 720° for four strokes).
If I have worked it out correctly, wired as 1+4, 2+3 on 4 squirts alternating, each cylinder gets a half squirt on a closed valve and a half squirt on
an open valve.
Wired as 1+3, 2+4 on 2 squirts alternating, 2 cylinders get a full squirt on an open cylinder and 2 cylinders get a full squirt on a closed valve.
Wired as 1+4, 2+3 on 2 squirts alternating would theoretically give strange fuelling as 2 cylinders get the fuel immediately and 2 cylinders get the
fuel after 1 revolution, rather than half a revolution with 1+3, 2+4 wiring.
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