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

Sat Apr 16 23:23:15 UTC 2005

I wouldnt exactly say "skipped" is a good word for notches # 1, 3 and 5 
(after sync) are the "begin dwell" points, necccessary if notches are 2,4,6 
are to be "coil fire" points (when cranking or/and in bypass mode 
anyways)There's no spark without a trigger to initiate dwell period.
Regards
WOT

----- Original Message ----- 
From: "Programmer" <lwester at lincsat.com>
To: <gmecm at diy-efi.org>
Sent: Friday, April 15, 2005 11:22 AM
Subject: Re: [Gmecm] Re: Running V8 with $A1 DIS code

>
> 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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>>
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