[Gmecm] Re: Running V8 with $A1 DIS code

Mon Apr 18 02:10:21 UTC 2005

I know of the diagram you speak of quite well (it's accuracy has been called 
to question quite often). In that diagram the waveform labled D is the 4X 
and the EST line is F, however they should be of the identical shape (50%)
EST is shown correctly as it's essentially IDENTICAL to reference (ie 
reference is used to create EST), just "delayed" to represent the advance on 
the next cylinder coming up on compression. (and lined up perfectly with 
reference) while BYPASS is low resulting in a fixed base timing of approx 10 
BTDC.
If you look closely at the diagram it becomes obvious that something is 
wrong as the rising edges of reference (begine dwell) is at varing spots 
with respect to the TDC lines. I have scoped this on a 1999 STS engine and 
found it to be 50%, I dont believe the Auroras were any different, but you 
knever know!

4cylinder DIS reluctor has 6 equally spaced + 1 sync
The 4 cylinder IS a 2X reference which as you suspect is a 33% duty(dwell) 
66% wait state (60/120 degrees) so the rising edge of the 60 degree waveform 
(dwell begin) coincides with approx 70 BTDC (thank heavens for current 
limiting) then on the trailing edge>spark at 10BTDC, then 120 degrees low 
(ignore one notch) . Check you email I sent you a waveform diagram for the 
4cyl. Your idea of using it for the Northstar may work if on the Aurora the 
reference is in fact 33% as well. Please email me if you ever can absolutely 
ascertain this.
Regards
WOT

----- Original Message ----- 
From: "William Lucke" <william.lucke at highspeedlink.net>
To: <gmecm at diy-efi.org>
Sent: Sunday, April 17, 2005 7:32 PM
Subject: [Gmecm] Re: Running V8 with $A1 DIS code

> The information contained in the Aurora shop manual laid out a diagram of 
> all signals. It called out the 4x as high for two pulses of the 24x (5* 
> BTDC - 25* ATDC), then low for 4 pulses of the 24x.
> The gentleman on whose behalf I'm posting here scoped it an confirmed 33% 
> DC. Since he did his own wiring harness (a large and complicated task in a 
> N* Fiero), I assume he's sufficiently competent to probe the correct pin. 
> My manual confirms pin C.
>
> Ok, what does the reference signal for a 4 cylinder look like? Where 
> relative to TDC does it go high or low?
> If we used a 4 cylinder mask and just doubled base timing and timing table 
> entries... that might work. What mask would you recommend for getting 
> started?
>
>
> Will
>
>
>>Date: Sat, 16 Apr 2005 19:22:41 -0600
>>From: "WopOnTour" <wopontour at hotmail.com>
>>Subject: Re: [Gmecm] Re: Running V8 with $A1 DIS code
>>
>>Really?
>>Every N* IGN REF I've ever scoped was 50% (toggles every 45 degrees to
>>create a 4X) The only IGN REF I've ever known not to be 50% is the 4
>>cylinder engines- which are 60/120 (33%) What pin are you scoping, should 
>>be
>>PIN C (sometimes labeled "fuel control" in the schematics)
>>Regards
>>WOT
>>
>>----- Original Message -----
>>From: "William Lucke" <william.lucke at highspeedlink.net>
>>To: <gmecm at diy-efi.org>
>>Sent: Saturday, April 16, 2005 6:46 PM
>>Subject: [Gmecm] Re: Running V8 with $A1 DIS code
>>
>>
>> > That's a little clearer... thanks.
>> >
>> > So the reference signal from a V6 coil pack is 50% duty cycle, right?
>> >
>> > I think we've found the problem... the Northstar reference signal is 
>> > 33%
>> > duty cycle.
>> > So on a shot pulse, the RPM calculated for that pulse would be 1.5 
>> > times
>> > actual RPM and the RPM calculated from a long pulse would be 2/3 actual
>> > RPM. The calculated RPM would bounce back and forth between these 
>> > values 4
>> > times per revolution... AIUI.
>> >
>> > Any way to get V6 DIS code--any mask--to run with this coil pack?
>> > How does a 33% DC 4X compare to the DRP's from a distributor?
>> >
>> >
>> >
>> > Will
>> >
>> >
>> >
>> >>From: "Programmer" <lwester at lincsat.com>
>> >>Subject: Re: [Gmecm] Re: Running V8 with $A1 DIS code
>> >>To: <gmecm at diy-efi.org>
>> >>Message-ID: <002001c541df$c8dbaf00$4250050a at WESTER2>
>> >>Content-Type: text/plain;       charset="iso-8859-1"
>> >>
>> >>
>> >>No coil pack event every 60 degrees--measurement event, yes.
>> >>My stupidity apologies to the masses...brain got interrupted by typing
>> >>again. By comparing the time between pulses on the DIS V6, after seeing
>> >>the
>> >>7th slot (sync pulse), every other trigger slot is skipped. The second
>> >>pulse
>> >>fires #2/#5, 4th fires #3/#6 and 6th fires #1/#4. There is no coil 
>> >>firing
>> >>event for the other trigger slots--although they're still
>> >>monitored/measured. This actually provides a better timing advance
>> >>signal/measurement.
>> >>Anyways...this is correct for the '730.
>> >>
>> >>Over and out.
>> >>
>> >>P.S. Take a look at the LS1 code, someday...you'll see some pretty wild
>> >>timing values.
>> >>
>> >>Back to lurk mode...
>> >>
>> >>Lyndon.
>
>
>
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