general efi questions

[steve ravet]

Brian Dessent wrote:

> should be [mostly] closed)?  Or, stated another way, why in the world
> would you wire injectors in parallel, why not let each one have its own
> control signal?  And, why fire all four at once on startup?

It makes the hardware and software simpler and cheaper.  Read in the
gmecm or diy_efi archives about batch fire versus SEFI for pros and
cons.  There's a ton of good info in there for someone coming up to
speed on EFI.

> 
> - Advance/retardation is ideally based on degrees but the computer
> ultimately works with time.  Does the ECU just use the RPM data from the
> crank angle sensor to convert timing from degrees to ms?  I can't recall
> at the moment but I think the angle sensor sends out a single pulse for
> every rotation of the distributer, or it could be 3 pulses per rev.

I don't know about your Mazda but GM ecms use the tach signal for rpm, a
pulse for each spark event.  RPM related functions in the ECM then have
to know the number of cylinders to determine RPM.

--steve

-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
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