FW: Electronic timing advance

[Bruce Plecan]

-----Original Message-----
From: rauscher at icst.com <rauscher at icst.com>
To: DIY_EFI at efi332.eng.ohio-state.edu <DIY_EFI at efi332.eng.ohio-state.edu>
Date: Monday, January 25, 1999 9:15 AM
Subject: Re: FW: Electronic timing advance

At one time I had a dozen or so esc on the bench, what exactly do you need
to know?.
In crash testing them, using a 555 to generate the KS they all seemed to
listen
to 2 frequencies.
If you want I think I got the diagrams for the 555s to generate the KS
signals.
The 555 generators kinda overwhelm the ESC so the results aren't terribly
accurate, if your tuning them.
Bruce


>To trigger a 555 directly from the ESC module, do this:
>    a) Run 555 from 12v car power (same for ESC module)
>    b) Place a 10K ohm resister from pin 2 (trig) of the 555 to +12v
>    c) Output of ESC through a .01uf disc capacitor to
>        pin 2 of the 555.
>This in effect, causes a short low going pulse on the trigger input of
>the 555 whenever the ESC output goes low. The ESC output normally
>sits at ~10volts, and pulses low for +-10-30msec depending upon the
>severity of the knock.
>Then as Bruce states below, run the 555 pulse duration long enough that
>you can see the LED light. Or, place a small piezo beeper on the 555
>output for an audio indication. (Depending on the type of piezo, you may
>need another 555 enabled from the first, to create the tone freq).
>BobR.
>Who now has a 305 truck ESC module on the bench, trying to find
>out the how/what/why/where of this unit.
>ubject: Re: FW: Electronic timing advance
>>If your running a ESC Module, they have a diagram for a DIY one at the GN
>>Ttype
>>site,  or just us a 339/any comparator to the input of the KS to the ecm,
>>have
>>it trigger a 555 as a monstable for a sec., and use it's output for a LED,
>>relay
>>etc..   Some of the GN Ttype vendors (ie ATR, I think) have an animal for
>>sale.
>>   If your car doesn't have a ks then buy a matching ESC Module, and
>>matching knock sensor (well for gm's anyway).  and wire it up
>>I think the bias voltage from the esc to the ecm is 7v.  Set up the
>>comparator for 6, and then just a "filtered""real" knock will trigger it.
>>  I have played mix, and match with them, and while there is some
>>difference for those having trouble reading plugs, any thing is better
>>than nothing.  Like I'm currently using a v-8 ks with a 231 ESC Module
>>and for my combination it's perfect.
>>Bruce