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

Sun Apr 17 00:46:25 UTC 2005

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

-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.308 / Virus Database: 266.9.13 - Release Date: 4/16/2005