I'm installing my ms2 (v3) following the instructions on aaroncake's site.
The specific page I'm reffering to is
http://www.aaroncake.net/rx-7/megasq...Megasquirt.asp
about a third of the way down where it shows the master wiring schematic and below that where it shows to wire the injectors.
You can view the wiring schematic directly by copying this into your browser:
http://www.aaroncake.net/rx-7/megasq..._schematic.gif

My question is this. The MegaSquirt appears to have 4 injector outputs, so why aren't we controlling each injector individually?
Why have both injectors firing at once, instead of alternating between rotors? It seems to me like the same thing as wasted spark, but instead like wasted fuel :P

There are 2 wires for inector bank one, and two for the other. In the wiring schematic, it shows the two wires for each bank being combined and then run up to the engine as one, where the ground of both of the primary injectors are wired to this now one INJ bank 1 wire, and the same is done for the secondary injectors, attached to bank 2.

I'm not saying that these are being wired wrong, or that I don't agree that this can work, I simply just do not understand why we are doing it this way and would like an explaination.

 

Megasquirt uses a batch firing order for the injectors, the new MS3 with ms3x (unless im mistaken) uses both batch and sequential so you can choose.

batch firing is being able to fire a set of injectors at the same time, sequential is the ability to fire each injector independently

 

Alright, so it's just a matter of megasquirt 2 not having that capability. Thanks that clears it up.

 

ms2 can run sequential for up to 4 cylinders, but not when rotary trailing ignition is enabled. They use the same timers.

Ken

 

True, it "appears" to have 4. In actuality, unless it is modified, there are only two internal driver FET transistors for all the injectors. Internally, they each split to take up 2 pins each in the header, totaling 4 pins used. Outside the box Aaron shows them brought back together for a single wire run to the injectors and then split out again. I suspect, although I didn't design the system, that this was done to share the current for low Z injectors thru the 37 pin connector. The current rating for the DB is not very high. In order to run 4 sequential injectors, I think you would have to add 2 more driver circuits or get one of the add-on boards.

Ken, is this correct?