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

Sun Apr 17 01:22:41 UTC 2005

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.
>>
>>
>>
>>----- Original Message -----
>>From: "William Lucke" <william.lucke at highspeedlink.net>
>>To: <gmecm at diy-efi.org>
>>Sent: Friday, April 15, 2005 9:45 AM
>>Subject: [Gmecm] Re: Running V8 with $A1 DIS code
>>
>>
>> > Sounds like you're measuring advance in distributor degrees...?
>> > 55 degrees of ignition advance is 27.5 distributor/cam degrees... which
>> > would not be into the previous cylinder's timing...
>> >
>> > Also, the crank timing wheel has little bearing on the signal the DIS
>>sends
>> > to the ECM. Quad 4's, believe it or not, also have a 6+1 timing wheel. 
>> > The
>> > Northstar has a 24+8 wheel and two sensors 27 degrees apart, but the 
>> > DIS
>> > still outputs one RP per ignition event.
>> >
>> > DIS V6 fires every 120 crank degrees... it just fires two cylinders 
>> > when
>>it
>> > does.
>> >
>> > This 7730 is for a different project, not mine. Did you get my last 
>> > email
>> > about the stock N* PCM?
>> >
>> >
>> > Will
>> >
>> >
>> > >From: "Programmer" <lwester at lincsat.com>
>> > >Subject: Re: [Gmecm] Running V8 with $A1 DIS code
>> > >To: <gmecm at diy-efi.org>
>> > >Message-ID: <002001c541cc$b62837b0$4250050a at WESTER2>
>> > >Content-Type: text/plain;       charset="windows-1250"
>> > >
>> > >I don't drop in much anymore, but....
>> > >
>> > >L4 = 180 crank degrees (DIS with wastespark /2)
>> > >L6, V6 = 120 crank degrees for firing event. (DIS with wastespark /2)
>> > >V8 = 90 crank degrees for firing event
>> > >
>> > >Camshaft 1/2 speed of crank
>> > >
>> > >L4 = Cam 90 degrees for valve/CR/ignition event
>> > >V6 = Cam 60 degrees for valve/CR/ignition event
>> > >V8 = Cam 45 degrees for valve/CR/ignition event.
>> > >
>> > >Note that with these timing events the maximum distributor timing 
>> > >allowed
>>?
>> > >L4 = 90 degrees of ignition timing (in theory, guys)
>> > >V6 = 60 degrees of ignition
>> > >V8 = 45 degrees before firing the next pole.
>> > >
>> > >These are theoretical, as trying to add 45 degrees ona V8 would just 
>> > >fire
>> > >the next cylinder at the wrong time...
>> > >
>> > >Too much "initial" advance in EFI, and the entire curve is 
>> > >added--leading
>> > >cause of detonation and other issues.
>> > >
>> > >One of the reasons for DIS was to allow for even "more" timing advance 
>> > >in
>> > >some cases. Directly looking at the LS1 code (as an example), many 
>> > >V8's
>>have
>> > >very high timing values (very low load, mid to high RPM) of as high as
>>55+
>> > >degrees ignition timing--which if in a conventional distributor 
>> > >setting
>> > >would fire the next cylinder instead of the one you want to fire !
>> > >
>> > >If the crank trigger has 6 slots on the crank (which every V6 should
>>have),
>> > >there is a coil pack "event" every 60 degrees of crankshaft 
>> > >rotation--not
>> > >120 at the crank. Remember--DIS has in reality, twice the # of firing
>> > >events--power and waste at each cylinder for each crankshaft 360 
>> > >degrees
>>if
>> > >the coil pack is grouped.
>> > >  The earlier V6 Cavalier, as an example, had 6 slots on the 
>> > > crankshaft
>> > >spaced 60 degrees apart, with a 10 degree offset (#7) slot to 
>> > >determine
>> > >which is #1. This additional slot was used for both timing 
>> > >calculations,
>>and
>> > >RPM inputs to the ECM/PCM. Hope this is making sense...
>> > >
>> > >Individual coil pack or COP is 120 degrees at the crank for a V6.
>> > >
>> > >Lyndon.
>> > >
>> > >
>> > >----- Original Message -----
>> > >From: "David Haggard" <david at newcovenant.com>
>> > >To: <gmecm at diy-efi.org>
>> > >Sent: Friday, April 15, 2005 5:58 AM
>> > >Subject: RE: [Gmecm] Running V8 with $A1 DIS code
>> > >
>> > >
>> > > > Oops..... Every 60 degrees of CAMshaft rotation. How easy it is get
>>this
>> > >stuff mixed up!
>> > > >
>> > > > While my thought process of how the number is determined is 
>> > > > different
>>from
>> > >HTH's (IGN REF), the idea is the same. In my mind, it all eventually 
>> > >goes
>> > >back to the old-fashioned way of determining when to fire a coil-- a
>> > >distributor being turned and timed by the camshaft.
>> > > >
>> > > > David
>> > > >
>> > > > > -----Original Message-----
>> > > > > From: gmecm-bounces at diy-efi.org
>> > > > > [mailto:gmecm-bounces at diy-efi.org] On Behalf Of WopOnTour
>> > > > > Sent: Thursday, April 14, 2005 9:38 PM
>> > > > > To: gmecm at diy-efi.org
>> > > > > Subject: Re: [Gmecm] Running V8 with $A1 DIS code
>> > > > >
>> > > > > Actually 6cyl DIS fires a coil every 120 degrees, not 60 But
>> > > > > I agree with the 45.
>> > > > > IIRC reference angle is the #of degrees between the IGN REF
>> > > > > voltage state switches. Every 60 degrees on the V6
>> > > > > (triggering on every trailing edge or 120 degrees) and on the
>> > > > > 8 cyl that would be 45 degrees (triggering every 90
>> > > > > degrees)
>> > > > > HTH
>> > > > > WOT
>
>
>
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