[Gmecm] a question of timing

[davesnothereman at netscape.net]

AS&M really seems to live by the "money is no object" philosophy.  The 
LS1 provides a cam signal, which can be sent directly to the Edist.  
The OEM crank signal is worthless to the 7749, but the product info for 
the Edist says "Compatible with LS1 engine" then adds a footnote which 
says "must use 4X crank signal."  Gee... that's exactly the signal the 
7749 needs.  Hmmm... it's looking more and more like the OEM EFI can be 
used.  Arizona Spend&Money say " I doubt that the GM PCM that you 
intend to use will have a dwell table compatable with the LS1."  But 
the Edist product info says "replaces mechanical distributor on older 
engines" implying that the E-dist works with a "table-less" distributor 
(I have tech info from FAST implying points can be used as a trigger).  
And the 7749 is programmed to maximize dwell on a mechanical 
distributor system, so I really don't see an issue.  And to further 
things along, I happen to know the 7749 works with E-dist.

The only zig to the zag is that there is no "bypass mode" built into 
the Edist.  There are likely a couple of ways around this.  If you can 
power a traditional distributor ignition module such as the 7749 is 
typically connected to, then you can probably use the coil trigger line 
to trigger the Edist.  This should work, but I don't know of a working 
example so I won't say it will definitely work.  The second way that I 
know works is to wire the EST line from the 7749 directly to the Edist. 
  Since there's no signal on the EST line until (1) reference pulses 
exceed a threshold count, and (2) crankshaft speed achieves a threshold 
limit, you'll have to adjust these two limits to allow reference pulses 
to occur fairly quickly during cranking.  The downside?  It's possible 
that slow cranking speed (during winter, low battery, or tired starter) 
may cause problems with correct ignition pulse generation.  I've never 
heard of a problem on the 7749 EDist vehicle that I'm familiar with, 
but it may have never experienced the right conditions.

Keep the wheels turning.

Zaphod


 -----Original Message-----
 From: Mike V <efi at dyakron.com>
 To: gmecm at diy-efi.org
 Sent: Sun, 19 Mar 2006 15:48:07 -0500
 Subject: Re: [Gmecm] a question of timing

 I dug through my old emails to verify. Slight correction.
 Fast didn't respond to my emails a little over a year ago, so I
 emailed an eDist dealer with questions (AZ-Speed?)
 Response below

 <<=====<<snip from Jan 2005 message >>=====>>
 Mike,
  I doubt the Edist will work without a cam sync and it responds to the 
triggers from the FAST ECM. The Edist does not create the dwell timing 
either. That is accomplished in the FAST ECM. I doubt that the GM PCM 
that you intend to use will have a dwell table compatable with the LS1. 
Most of the applications we have done used a MSD DIS to drive the 
coils.  I am not sure where to locate the manual. It comes with the 
Edist. Fire off an email to FAST and see if they can forward one to 
you.
  BigStuff has a new system out there that can do it all in one box. 
Drives the LS1 Smart Coils directly and will also run the ASA LS1 coils 
direct. It also has Electronic Trans control in the same box. Their new 
BigStuff Gen III is priced at $1800 base and comes with WBO2 and wiring 
harness. It includes software and programming cable. The LS1 package is 
more money but they have it at $2495 including DAI option. DAI is data 
logging internal where no lap top is required in the car to log data. 
All channels are logged at ultra high speed to RAM on board the ECM. 
This can be uploaded after the run and is easily enabled by a single 
toggle.
 Dan


 _______________________________________________
 Gmecm mailing list
 Gmecm at diy-efi.org
 http://lists.diy-efi.org/mailman/listinfo/gmecm


___________________________________________________
Try the New Netscape Mail Today!
Virtually Spam-Free | More Storage | Import Your Contact List
http://mail.netscape.com