4cyl 7747 ( was Netres availability)

[Shannen Durphey]

Hi, Dan.

If you are set on using the 7747, how about some more basic tests?  Make a .bin
with a bad checksum to force limp mode.  In limp mode, the ecm should not be
supplying a 5V signal to the distributor.  The timing should remain on base
timing until something around 2000 rpm then it should advance rapidly to 20+
additional degrees.  Engine operation should be much more stable with timing
control fixed.  If you cannot find the timing mark with the light, you have
additional problems.

Does the timing procedure for the 165 require disconnecting the tan/blk bypass
wire, or jumpering terminals A to B in the ALDL.  You may want to try
disconnecting the bypass connector as Bob R suggested if you have not been doing
that.

The knock module can be connected, and a knock sensor can be electrically
connected to the module and engine block with jumper wires but not mechanically
connected.  There should be no issues with detected knock if this is done.

How stable are your vacuum readings?  If the vacuum fluctuates considerably,
timing will also fluctuate.  4 cylinder engines do produce larger vacuum spikes
than 8 cylinder engines.

If the issue comes down to fueling (which it does not appear to be righ now) you
might try looking at the asynch fuel flag at 0x000E to see what effect changing
it will have.  Also, I believe someone mentioned there are other ways to prevent
synchronous fire mode from occurring.  One other option for experimenting is to
tie the REF signal to the 165 and the 747, but use the 747 to control bypass and
EST functions.  This would ensure there's a steady supply of fuel while checking
timing.  POT's or fixed resistors could be used to supply engine data signals to
the 165, since it will only be used to keep the engine idling while checking
timing.


Just some thoughts.
Shannen

Dan Griffin wrote:
> 
> ----- Original Message -----
> From: rr <RRauscher at nni.com>
> To: <gmecm at diy-efi.org>
> Sent: Saturday, August 18, 2001 10:53 AM
> Subject: Re: Netres availability
> 
> >
> > With the '747 in place and the ignition bypass open, does the
> > timing mark line up properly ( 0 to 6 deg, whatever your base
> > is set to)?....  No...its suppose to be about 6...its nowhere in sight, Id
> say there are major diffrences in distributors, on mine, you connect a - b
> in the aldl to set timing.. V8 has a timing connector??
> 
>  Also, did you change the bin setting it as a 4-cylinder?
> Whoops, I knew I forgot something,....Ok its changed, now truck runs worse,
> herky jerky bad and backfiring again....wierd...
> >
> > I'd also try to get everything hooked up as factory designed. Little
> > things can make a big difference. Even with the knock tables zero'd
> > out there are still other effects of not having an ESC module.
> I was afraid of that, I doubt an esc would work since theres so much other
> eng. noise..
> Is'nt there a way to disable the esc to make the '747 happy using a resistor
> or something?  seemed like I remember something in the archives about that
> but couldnt find it....
> >
> > BobR.
> >
> What is your base timing value in the 7747 .bin?  What is the base timing of
> the
> distributor?  Are you using an adjustable type timing light or a fixed type
> timing light?
> 
> Shannen
> 
> 0 in the bin...6 with '165 plugged in....fixed type....
> 
> RR , you hit the BINgo. No ESC module. Plugging in a 4cyl ESC
>     and as indicated set for 4 cyl in bin could help immeasurably.
>     To add to the fray ,** if 4 cyl  has noise problems or a few exh
> leaks,**
>     and fixed timing vs map,tps.rpm , It's easy to envision the "herky
>     jerky" movements. Zeroing the Ks tables is bandaging more serious
>     Run time tuning problems present , IMHO.
>     Len
> 
> Yeah, it does all that, but after 181,000 mi. I cant complain...I didnt know
> there was a esc for the 4cyl?? At any rate its probably a diffrent type than
> the v8 and incompatible with '747...
> Dan
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