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MS: Injector wiring
Benzine - 9/9/08 at 07:07 PM

I'm slowly getting there with wiring up my MS (TPS working, was great watching the gauge move on the laptop screen )

Now I've got round to injector wiring and I'm a bit confused as to which wires go where on the megasquirt. So I have 2 banks of 3 injectors and it's different to how they look in the diagrams I found.



Figure 1 is a BMW straight 6 MS engine diagram I found

Figure 2 is the standard megasquirt diagram (4 cylinder) for MS2 V3 (which I'm using)

Figure 3 is how my injectors are wired at the moment.

I don't know enough about wiring/engines to know when they need to fire etc. Firing order is 1-5-3-2-4 if that info is needed.

martyn_16v - 9/9/08 at 07:22 PM

quote:
Originally posted by Benzine
Firing order is 1-5-3-2-4 if that info is needed.


Is 6 just along for the ride?

It doesn't really matter, as MS batch fires the injectors (i.e. it doesn't actually fire them at any particular engine position, just once per cycle). I like to wire mine up so that the two injector banks are alternating through the firing order, so on a 1-3-4-2 I'd go for 1 and 4 on one bank and 2 and 3 on the other.

Just do whatever makes the wiring tidiest

clairetoo - 9/9/08 at 07:22 PM

What you have will work fine - just be sure to set to 2 squirts per cycle .
Mine is wired as two banks , and I've no idea what the firing order is - it runs fine

[Edited on 9/9/08 by clairetoo]

mark chandler - 9/9/08 at 07:28 PM

Its not sequential injection, it just squirts irrespective of crank position in two lots so does not matter.

You could inject cylinders 1, 2 & 3 at once followed 4, 5 & 6.

Your picture is injecting 1, 3 & 5 followed by 2, 3 & 6.

In reality it makes very little difference.

Lots of older injection systems work like in same way, rover v8 in all classic range rovers for instance, v12 jags were more advanced and fired 4 banks, again irrespective of crank position.

Regards Mark

Benzine - 9/9/08 at 08:03 PM

quote:
Originally posted by martyn_16v
quote:
Originally posted by Benzine
Firing order is 1-5-3-2-4 if that info is needed.


Is 6 just along for the ride?

It doesn't really matter, as MS batch fires the injectors (i.e. it doesn't actually fire them at any particular engine position, just once per cycle). I like to wire mine up so that the two injector banks are alternating through the firing order, so on a 1-3-4-2 I'd go for 1 and 4 on one bank and 2 and 3 on the other.

Just do whatever makes the wiring tidiest


whoops, meant 1-5-3-6-2-4!

Will this wiring be okay then:




So will 3 injectors fire at the same time? Won't the cylinders be at different stages of the 4 strokes? I don't see how if there are 2 wires controlling 3 injectors how it can fire one of them :S I'm probably thinking too much


quote:
Originally posted by clairetoo
What you have will work fine - just be sure to set to 2 squirts per cycle .
Mine is wired as two banks , and I've no idea what the firing order is - it runs fine


Cool, I'll try remember that! Your car runs better than fine! (see my brown trousers for proof ) Thanks again for taking me out in your car and doing my wiring (which you're pr0 at )


[Edited on 9/9/08 by Benzine]

clairetoo - 9/9/08 at 08:32 PM

quote:
Originally posted by Benzine

Cool, I'll try remember that! Your car runs better than fine! (see my brown trousers for proof ) Thanks again for taking me out in your car and doing my wiring (which you're pr0 at )


[Edited on 9/9/08 by Benzine]

Aw shucks
I'd be happy to pop round and get it finished off and running when your ready ? It would be good practice for the next V6 Fury I've just started

mark chandler - 9/9/08 at 09:23 PM

If you are running without the second output board (flyback) make sure you do not fry the transistors in the megasquirt using ballast resistors, been there done that.

Old rover v8 flappy box systems have a nice resistor pack that you can get off ebay for pennies linky thing, just try and get a bit of the loom as well so you get the plug.

Regards Mark

Benzine - 9/9/08 at 09:35 PM

quote:
Originally posted by clairetoo

Aw shucks
I'd be happy to pop round and get it finished off and running when your ready ? It would be good practice for the next V6 Fury I've just started


That'd be awesome I've sourced an oil cooler which is on it's way, then it's just ignition leads and I have everything! Where did you get yours made? I need to start measuring up and getting some ordered

clairetoo - 9/9/08 at 10:05 PM

I got mine from Magnacore - not really locost , but since I needed ford coil plugs with mazda plug caps.....
They do an `on-line` specials order form so you can spec what you need , plus they were quite quick making mine up

matt_claydon - 10/9/08 at 07:45 AM

quote:
Originally posted by Benzine
So will 3 injectors fire at the same time? Won't the cylinders be at different stages of the 4 strokes?


Doesn't matter, the fuel will just sit in the inlet tract for a few fractions of a second until it's sucked in when the valves open. More complex systems use 'sequential injection' where the injection events are synchronised with the cylinder cycles, but the benefits are very slight.

MikeRJ - 10/9/08 at 08:21 AM

quote:
Originally posted by matt_claydon

Doesn't matter, the fuel will just sit in the inlet tract for a few fractions of a second until it's sucked in when the valves open. More complex systems use 'sequential injection' where the injection events are synchronised with the cylinder cycles, but the benefits are very slight.


And it's only sequential at low RPM when there is enough time for individual injector operations. It only helps with emissions and (to a small extent) fuel economy.