[Gmecm] [Diy_efi] V6 vs V8 netres

Thu Aug 11 20:20:53 UTC 2011

I'm working with a very small engine.  A Datsun 1.8L SOHC which I think will
make better torque with a small throttle plate.  I currently have a weber
38/38 on it which gives it a big bog until its somewhere north of 3krpm. I
have a weber 32/36 on a similar 1.6L and it seems to have no bog.  The ECM's
I currently have are all 7727's which only have one driver anyway.   I'm not
really sure if they can fire a TBI injector as I think its meant to run the
High Z injectors.

Is the only major drawback to the 7747 that it uses the slower ALDL?
I think I may go to the junk yard this weekend and find me a 7165 or two.
 Because there does not seem to be a lot of people using it for TBI

Has any one ever used a mechanical fuel pump to provide a TBI with fuel
pressure?

I know they have an internal fuel pressure regulator But I think
most mechanical pumps won't make the pressure needed unless the engine is
reved up.

-Avery

On Wed, Aug 10, 2011 at 9:00 PM, Bill Hamilton <scoutii76 at hotmail.com>wrote:

>
> The 2.5 1 barrel is 1.5 bore.
> My older 1 barrel like the crossfire TBI is 1 11/16.
> I normally recommend using the 2.8 2 barrel TBI if using the 7747 C3 ecm
> instead of combining the 2 injector drivers and firing 1 inj.
> It makes tuning easier.
> ------------------------------
> Date: Wed, 10 Aug 2011 12:37:31 -0700
>
> Subject: Re: [Diy_efi] [Gmecm] V6 vs V8 netres
> From: anisbet at gmail.com
> To: scoutii76 at hotmail.com
> CC: davida1 at hiwaay.net; diy_efi at diy-efi.org; gmecm at diy-efi.org
>
> How big were the TBI's on the 2.5L?
>
> -Avery
>
> On Wed, Aug 10, 2011 at 12:33 PM, Bill Hamilton <scoutii76 at hotmail.com>wrote:
>
>  Avery,
> Thanks for the additional references.
> I used to spend a lot of time on thirdgen. Some of that looks the same.
>
> I have used the V8 bins and netres for the C3 ecms(7747) on my 4 cyl
> conversions.
> I haven't tried it with the P4 memcals.
> I just grabbed a couple S10 2.5 TBI 7165 computers to play with.
> I have seen 3 different codes so far (53, 83a, 94) and it looks like the
> ignition systems are different.
> I've only found a couple bins for each code so far.
> But I would guess I could just use the G3 adapter and install the 2.5
> memcal in a newer 7427 PCM and adjust the cyl select on any starter bin for
> the 4 cyl. Then just use the C3 external ESC/KS if desired or just remove
> the knock all together.
> Gives a faster PCM to run the older engines and the optins for boost and
> electric fans code if needed.
> Not much different from the code59 work that's been done.
> Just gives more options with what's out there.
>
> ------------------------------
> Date: Wed, 10 Aug 2011 11:41:32 -0700
> Subject: Re: [Diy_efi] [Gmecm] V6 vs V8 netres
> From: anisbet at gmail.com
> To: scoutii76 at hotmail.com
> CC: davida1 at hiwaay.net; diy_efi at diy-efi.org; gmecm at diy-efi.org
>
>
> There has been a lot of work on building custom resnets and ESC's
>
> http://www.thirdgen.org/techboard/diy-prom/447242-730-727-749-memcal.html
>
> and
>
>
> http://web.archive.org/web/20080517110323/http://www.iroczone.com/resnet165.htm
>
> Have some info.
>
> There are more links in that thirdgen forum page.  I think they had the V8
> stuff figured out.  I was always more worried about the I4 stuff.
>
> Bill, did you use V8 memcals with I4 engines when you did conversions?
>
> -Avery
>
> On Tue, Aug 9, 2011 at 11:30 PM, Bill Hamilton <scoutii76 at hotmail.com>wrote:
>
>  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 <anisbet at gmail.com>
> *To:* Bill Hamilton <scoutii76 at hotmail.com>
> *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<http://us.mc1618.mail.yahoo.com/mc/compose?to=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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>
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