7747-4cyl experiment

[Eric S]

If you are looking for hacked 4 cylinder files, I am not sure which 
fourcylinder you are talking about, as I am here in 'mid conversation' I 
would try this website : www.geocities.com/jeremygonyou

He had a sunbird 4cyl turbo, he does eeprom editing and hacking, he may have 
some info listed on his site for his Sunbird 4cyl.  Try there, and good 
luck!

>From: "Dan Griffin" <slowfatslug at hotmail.com>
>Reply-To: gmecm at diy-efi.org
>To: <gmecm at diy-efi.org>
>Subject: Re: 7747-4cyl experiment
>Date: Tue, 21 Aug 2001 16:07:34 -0400
>
>
>
>----- Original Message -----
>From: rr <rrauscher at nni.com>
>To: <gmecm at diy-efi.org>
>Sent: Monday, August 20, 2001 2:15 PM
>Subject: Re: Netres availability
>
>
> >
> > Dan,
> >
> > In the '747 harness near the distributor there is a single
> > wire connector. The wire is tan w/black stripe. This
> > connector needs to be open to set the base timing. It opens
> > the bypass signal from the ECM and disables ECM control of
> > the timing.
>Ok, I disconnected it ( pin d5 )from the ecm end,( same as 165) since the
>fender well has to be removed to acsess the distributor on a 4cyl... Timing
>is now rock steady at "0"....it climbs to about 16 when I rev it up...makes
>no diffrence whether aldl pin a-b is connected or not...other than ses
>flashes...
>with eprom removed,( limp mode? )( 747 plugged in entire time ) timing is
>rock steady at "6" ..which is what I set base timing at with 165 plugged
>in...when I rev it up it  climbs to around 16 and occasionally jumps outta
>sight..
>with d5 and chip plugged back in, timing is around 30 - 40? from what I can
>tell, its way over there, the white paint dab sure helped... It still is
>kinda jumpy, even with knock tables zeroed, but not as bad as
>before...sometimes at idle I get double spark too...Idle never has been 
>real
>smooth, like it is in limp mode,or d5 unplugged..
>
>I like the resistor trick, cant I just hook it directly to the esc pinout 
>on
>ecm and ground it to any ground? Or is it mandatory to go through an esc
>module 1st.? Ill hafta find out what a esc module is...The 10mm nut on side
>of ecm looks like a good ground spot...Ive got about 2' of 747 harness with
>the ecm connector end..
>
>There is now some question as to what 747 base timing is.. "0" with d5
>unplugged,( more logical, imho)  or "6" with eprom out? I never moved
>distributor timing throughout test...
>
>
>snip<  What is probably happening is that only two of your cylinders are
>getting a fuel shot and the other two are just tagging along.>
>
>wouldnt I be able to see this? with timing light hooked to coil, pointed at
>tbi, injector fires everytime light shines...shouldnt it be spurt spurt
>then 2 dead spurts?
>
><This assumes
>you are only using one injector driver. This also assumes that you have the
>ECM bin set up for 4 cylinders, which may not even be an option in the 7747
>bin.>
>
>  Its only a winbin option.. I dont really undestand what its for, 
>everytime
>I burn a chip with it set to 4 truck runs worse...It runs good set 6 or 
>8...
>
><What is more likely happening is the ECM is trying to control the engine
>as a 6 (or 8) cylinder, and therefore the alternate injector firings are
>hitting each cylinder just in a very intermittent way. In other words, with
>a
>V8 bin, the ECM thinks the engine is turning only 500 RPM when it is really
>turning 1000 RPM.>
>
>wouldnt that screw up my idle speed? if idle is set to 800 then it should 
>be
>actual running at 400? I hope its not doing any of that...
>
>  <This would also put you in a leaner part of the fuel table.>
>
>the only code I get is 45 (rich).. although plugs look a little lean, light
>greyish...
>
><The bottom line is that a 7747 on a 4 cylinder is a misapplication. What
>you
>are running into is that demand for reverse engineered (hacked) 4 cylinder
>ECMs is very sparse.>
>
>Yeah, I know, thats why im experimenting with this...
>
>< You may have to do your own hacking of a known 4
>cylinder ECM, such as the 165 you already have.>
>
>Tried to, I dont know how to recognize what the tables, switches, constants
>look like in the dissasembly...
>
>< Maybe you ask the list for
>other hacked 4 cylinder ECM applications. JW>
>
>  tried that a long time ago, there arent any...
>Dan
> >
> > You'll need to do this before any other timing issues. If
> > the base isn't set right, then nothing else SA wise will
> > be right.
> >
> > For the ESC module use any one you can find. Just plug
> > one in. In place of the knock sensor try a 3.9K resistor.
> > (This is if you are not using a knock sensor). The resistor
> > goes from the ESC module to ground.
> >
> > Once you can get the base timing set things should get
> > better.
> >
> > BobR.
> >
> >
>
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