FW: Electronic timing advance

rauscher at icst.com rauscher at icst.com
Mon Jan 25 14:01:16 GMT 1999



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.


> -----Original Message-----
>rom: Charles Brooks <cbrooks1 at mail.tqci.net>
>o: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>ate: Friday, January 22, 1999 7:36 PM
>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

--






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