[Diy_efi] [Gmecm] V6 vs V8 netres

Wed Aug 10 06:30:16 UTC 2011

This topic may be worth a discussion. When using the C3 ECMs I have had issues with the netres being cyl specific.(some have claimed it doesn't matter)I normally just pick a netres and bin for the engine I am tuning.But I also run the same ecm(normally the 7747) on 4 cyl conversions.For those I try to use the V8 based systems. When I pull the memcal chip it will still run on the netres but obviously at half idle speed.I've even ran both injector drivers to 1 injector on a 1 barrel throttle body. There is also documentation from RBob(RR) on clipping one leg to convert the V6 netres for use on the V8s.(I have it saved in a file) But then we get to the P4 and others.I Used the 7427 on several engines and also converted it to run MPFI. I started with the 4.3 CPI system and run it on a V8.There is also documentation on simply running the C3 ESC/KS instead of the memcal mounted filter and P4 KS. Is the 7730/7727 or even the 7165 that much different?  Can you simply clip a leg (solder in a resistor) on the netres to change a V6 to a V8 module?
 From: davida1 at hiwaay.net
To: anisbet at gmail.com; diy_efi at diy-efi.org; gmecm at diy-efi.org
Date: Tue, 9 Aug 2011 18:40:16 -0500
Subject: Re: [Diy_efi] [Gmecm] 181 merc 730

You must get a 4-cylinder MEMCAL. This is the 
module that contains the chip (with program) and the analog circuitry which 
determines the knock-sensor filtering and the number of cylinders.

You'll get a Cylinder Select error if you make a 
4-cyl program and use it on a 6 or 8 cyl memcal.  The actual EPROM is the 
same and the code will run, but it will see a mismatch between the MEMCAL's 
hard-wired cylinder select and the program's cylinder constant.

The ignition timing is calculated differently for 
each style engine because there's a different number of degrees of crank 
rotation between firing impulses for 4, 6, and 8 cyl.

Even if you use an emulator, it still 
needs the correct MEMCAL for the engine configuration.

Sincerely,
David 

  ----- Original Message ----- 
  From: 
  Avery Nisbet 

  To: Bill Hamilton 
  Cc: truckeez at yahoo.com ; diy_efi at diy-efi.org 
  Sent: Tuesday, August 09, 2011 6:25 
  PM
  Subject: Re: [Diy_efi] [Gmecm] 181 merc 
  730

The Rom is on the moates.net 
  ftp site.  And code59.org has a hacked 
  version.

  I think this is more getting the ECU to run the code with the right L4 
  ESC and knock setup.

  -Avery

  On Tue, Aug 9, 2011 at 4:22 PM, Bill Hamilton <scoutii76 at hotmail.com> 
  wrote:

    I have a turbo sunbird ecm on my shelf if you need me to read 
    the chip.

Bill

    Date: Tue, 9 Aug 2011 16:08:24 -0700
From: anisbet at gmail.com
To: 
    truckeez at yahoo.com
CC: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] [Gmecm] 181 
    merc 730

You can hack the V6 prom to change the cylinder count 
    but you will not have an ESC.  Im not sure if the ECU's run with out 
    them.

    These setup of the knock stuff.  And kinda configure the ignition 
    too.

    I'm trying to run a datsun 510 off of one of these ECU's  I found 
    the memcal from a quad four to work ok.  The iron duke didn't seem to 
    work but it could have been bad.

    Oh remember to add diy_efi at diy-efi.org to your CC so everyone else can see 
    it.
    -Avery

    On Tue, Aug 9, 2011 at 3:08 PM, alan mays <truckeez at yahoo.com> wrote:

          Oh No -back to the hard to find.... thanks for your input 
            but wouldn't a 730 from something with a dis work?

--- On 
            Tue, 8/9/11, Avery Nisbet <anisbet at gmail.com> wrote:

From: 
              Avery Nisbet <anisbet at gmail.com>
Subject: Re: [Gmecm] 
              181 merc 730
To: "alan mays" <truckeez at yahoo.com>
Cc: gmecm at diy-efi.org
Date: Tuesday, August 9, 
              2011, 4:46 PM

              You need the 4 banger prom from a turbo sunbird.  They 
              have it on the code59 site.  Its so it will work with the 
              ignition. 

              -Avery

              On Tue, Aug 9, 2011 at 2:04 PM, alan mays <truckeez at yahoo.com> 
              wrote:

                            OK I remember this from a while back-It would 
                            make life so much easier---IF I could get on the code59.org site.   
                            Someone mentioned the ECM doesn't really know how 
                            many injectors its firing  ,  So here is 
                            another question---  should i just get a 730 or 
                            at least the eprom from a 3.1 gm to start with since 
                            the "shaky II" --Merky II 4 banger is 3 ltr??  
                            would that simplify more as far as having to change 
                            values in the bin files?  here is a pic of the 
                            intake model for carbs--I haven't got a lt1 intake 
                            yet to make injector bung plugs to model in but they 
                            will be pointing at the back of the valves.
                            http://www.peachparts.com/shopforum/showthread.php?p=2767390#post2767390

                            "Alan, a 1227730 will 
                            work with the TPI harness or the Sunbird 
                            harness.  It MIGHT take a re-pinning of one or 
                            two wires but not have diagrams in front of 
                            me.

                            Is this a turbo'd 181? 
                            That will be neat!

                            Both the 1227749 and 
                            the 1227730 will run Code59 for boost.  The 
                            7730 can not run a TBI but the 7749 can run a TBI. 
                            This is because the 1227749 has a peak/hold injector 
                            driver but the 7730 has only saturated 
                            driver."
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