Knock sensing and retarding ignition

[Huw Scourfield]

When I built my system based on the 16f877 I merely used a single transistor
as a buffer between the bosch module and the pic, no problems with this at
all. If going to the trouble of using a pic why not design a complete
ignition system? Do away with the dizzy altogether. Mine used a reluctor
dizzy (metro) with the PIC detecting the zero crossing directly(it wasn't
happy at low cranking speeds, needs some amplification IMHO), the pic
calculated the correct spark timing based on load/speed and drove the bosch
module(single, hence the dizzy was retained). Beware working in
useconds/mseconds when dealing with petrol engines, engines work in degrees,
you really need to convert processor time to engine degrees if you want
repeatable delays at all engine speeeds. If you want more info get back
to me and I'll dig it out.
    Huw
----- Original Message -----
From: Stephen Webb <swebb at netlab.uky.edu>
To: <diy_efi at diy-efi.org>
Sent: 24 January 2002 20:32
Subject: Re: Knock sensing and retarding ignition


> > I have been thinking of doing the same thing to replicate vac advance on
a
> > NA engine.  For an ignition driver, use something like the injector
driver
> > on the MegaSquirt.  It could then directly drive the coil or be seen by
the
> > ignition module as points.
>
> I would like to interface to the stock ignition control module for a few
> reasons.
>
> 1.  It has automatic dwell control.
> 2.  I will be able to keep all of the stock wiring, and easily be able to
> take out the ignition retard controller.
> 3.  It gives me a sort of level of protection from any inductive kick from
> the coil (whether it really protects my circuit or not, I don't know, but
> it makes me feel better)
>
> -Steve
>
>
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