[Diy_efi] Fixed Frequency Injection

[Daniel R. Nicoson]

As you figure out you frequency versus range of pulse widths, remember the
minimum pulse width that actually delivers any fuel for typical 19#
injectors (Ford) is 1-2 ms.

Why not just bank fire, triggering once per two revolutions off the spark
primary signal?  You could probably do a simple analog system that feeds off
a MPX4250A MAP sensor, the ignition trigger signal and RPM.  Possibly better
than a carb, not as good as a microprocessor based system.

Just a thought.

Dan

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of Phil Lamovie
Sent: Friday, July 23, 2004 2:26 PM
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Fixed Frequency Injection



Hi Paul,

Bosch "K" Type injection is zero frequency variable flow.

It is quite capable of reaching early 80's emissions levels

The problem with fixing the frequency is getting through the odd
double dose vs half dose of fuel as you go from zero rpm through
to 1800.

If you inject very often then you can overcome this partially.

Your chosen rpm allows about 60 ms of injection events so you could do
7 or 8 small pulses

I can't see where the savings in hardware or software is going to
be made.

You still have a variable pulse width injector, it's just running off
an oscillator of some type.

At most you save a connection from the alternator to  the ecu for rpm
sensing

Am I missing something ?

Phil

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