Subject: Re: 034 EFI

[Marc Swanson]

> Except at low RPM (ie. idle), when you can get slightly lower
> emissions by timing the injection to a certain point in the cycle,
> it doesn't really matter when the injectors are fired.  Remember they
> fire at the back of the intake valve, not into the chamber itself.
> In fact, when developing high power, the injectors are likely to be
> on 85% or more of the time.  To make things easy in the ECU, the injectors
> often are fired all at once - known as batch mode.  Thus each cylinder gets
> its injector fired at a different point in its cycle.

Yep, this all came clear to me about 10 seconds after my initial post.  As
you say, nothing wrong from a performance standpoint using a batch mode
system.

> When using a crank sensor, if you want to determine compression/exhaust
> stroke, some kind of cam linked sensor is required.  On the MC and 3B
> engines, it's a hall sensor in the distributor with one window
> centered 62 degrees BTDC on Cyl 1.

Hmm.. could you get away with a division circuit?  It would be a little
akward since you might have to crank the engine over a few times before it
could calculate this...  I don't think the fact that one revolution must pass
before the circuit can slow down the engine is a big factor since changes in
rpm don't happen quickly enough to be a problem (I think!).  Do any OEM's do
this?

Thanks

-Marc-
87 4ktq
88 90q