Switches or relays?

[bill.shurvinton at nokia.com]

I assume you would be using 2 megasquirts, as it would be challenging in
the least to get fuel and ignition in the same board unless you were
using a very basic straight line advance curve. 

I'm not sure why you would want to go coil per plug rather than wasted
spark, but the TECII web site has some stuff on this. If I remember
right, with the packs they use you ground the unwanted output.

On the injector side, I've found 2 options looking at doing this for my
rotary.

Option 1: replicate the injector firing circuit for 6 injectors. Use
spare outputs from the MCU to select which injectors to fire (AND select
line and firing control)

Option 2: Use a FET to either high side or low side select the
injectors. High side (12V) is possibly easier to wire in. But
topologically this is almost identical to option 1.

The fun may come if you are injecting more than 1 cylinder at once, as
you have to start a new squirt before the old one is finished (caveat,
depends upon application, injector size, RPM, jada jada). I'm about half
way through the code mods to handle this on a rotary, although I won't
know if the code works until I get my megasquirt built.

And of course you need to sort some sort of CAS. That's easy on the
rotary as you only have 2 rotors,even though it looks like a 6 cylinder
engine. Haven't though of a 'simple' way to do it with 6 though.

Sequential is much more tricky than batch.

Bill

-----Original Message-----
From: ext Mark Bottorff [mailto:bottorffinator at yahoo.com]
Sent: Thursday, November 08, 2001 6:52 PM
To: diy_efi at diy-efi.org
Subject: Switches or relays?


I have some ideas about using batch fire coil packs
sequentially and using the Megasquirt for sequential
EFI.

Coil packs:
On my car ('88 Supra turbo) there are 3 sets of coil
packs that fire 2 plugs at a time. There is a seperate
connector for each coil pack. If I got another set of
coil packs, and plugged the connectors into some sort
of relay that would switch between coil packs as
they're actived, it would fire one plug at a time. The
problem is that there would be an empty spot for
another plug wire. If I were to "Y" 2 plug wires
together, would I get twice the spark, or that blow
the coil packs?

Sequential EFI:
Using the same sort of relay from above, but with 3
outs and and one in (for a 6 cylinder), couldn't you
make the Megasquirt fire one injector at a time?

Now the big question, does such a relay or switch
exist?

Thanks,
Mark Bottorff

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