Ignition module

PATTEEUW at etcv01.eld.ford.com PATTEEUW at etcv01.eld.ford.com
Fri May 12 18:49:14 GMT 1995

From: "Paul E. Campbell" <pecampbe at mtu.edu>
<lots deleted>
>All your processor has to do is be able to keep up with the important
>events (a reasonable response time), not diddle around with the timing for
>every single injector pulse.

You'll get a **BIG** debate on that statement from those "in" the industry !

<more deleted>
>b. How does one detect knock? And what do you do about it from an ignition
>point of view?

Knock is usually detected with a resonator type sensor.  The specific mounting
location that will give the best results is very engine dependent.  Spark is
usually retarded on an individual cylinder basis.

>c. What is the optimum spark voltage? The higher the better or is there some
>curve? How do you measure it? What are the dependent variables?

This is not my field of expertise, but I do know that the current Ford ignition
systems generate lower voltages than what we had 15+ years ago.  That high a
voltage just wasn't necessary.  Voltage is measured directly with special high
voltage probes (like those for measuring CRT voltages).  The bigger the gap on
the plug, the more voltage required to break it down.

>d. How long should you maintain a spark? <snip>

In general, the longer the better.  The big reason is to prevent possible
"flame out" on air/fuel mixtures with poor distribution.  There are two
approaches: high engery (long duration) or multiple restrike.

>How do you determine when to start the spark? I suppose this is related to
>the previous question.

There are lots of papers on MBT (bean best timing) and IMEP (indicated mean
effect pressure).  Higher IMEP = more power.

<more deleted>
>6. I've found the SAE Transactions in the local library (Michigan Tech.,
>Van Pelt), and they do pretty good but they don't even come close to having
>all of the papers SAE publishes. Some of the "unpublished" ones have been
>posted on this mailing list. Does SAE publish any other journals that have
>them or do you have to call SAE and pay for a specific paper for the majority
>of them? My bachelor's degree is in electrical engineering, so I'm used to
>the IEEE system where practically everything on anything has probably been
>published in some obscure journal, but this doesn't appear to be the case for

I have two small (<20 pg) catalogs from SAE containing many different books 
and/or collections of papers.  The first is called "SAE Publication on
Electronics" (catalog number 2884).  Lots of good books in here, such as
"Automotive Electric/Electronics Systems", "Automotive Handbook" (both from
Bosch), "Automotive Sensory Systems", "1995 Electronic Engine Controls" (a
collection of 16 paper), etc.  The other catalog (2894) has more general
automotive titles.  SAE phone number is 412-776-4970.


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