MAF and 89 Vet stuff

[TK]

hey Mark,

Is the 86 Y body the same as anything else? I don't remember working on it.
I think that's the 7703 ECM.

Terry

----- Original Message -----
From: Romans, Mark <romans at starstream.net>
To: <jwn at sgi.net>
Cc: <gmecm at diy-efi.org>
Sent: Saturday, August 12, 2000 10:12 AM
Subject: MAF and 89 Vet stuff


> Hi Jason:  I may be able to help you.  I had saved your messages intending
> to respond, just a time thing you know.
> I will try to go through each of your messages and respond to each
question.
>
> Question 1.
> Questions on MAF equipped 89 Vette.  Using Diacom for some time now and
have
> some questions about the different cell numbers used for fuel trims.  What
> tables dictate the amount of fuel used in open loop mode?  I understand
that
> in closed loop the MAF, O2, etc. determine the proper amount of fuel to
> deliver and adjust the short and long term fuel trims.  What is modified
to
> control the fuel delivered in open loop and PE?  I assume its the MAF
tables
> but I need educated on what the values represent.
>
> Response.  The BL is a group of cells numbered 1-15 in the following order
> (As I consult my hand drawn chart)
> Starting on the bottom left, left to right and each successive row goes on
> top of the prev one.  I put the zero's in front of the
> single digit numbers to preserve the spacing.
>
> 12-13-14-15    L             F
> 08-09-10-11    O            L
> 04-05-06-07    A  or        O
> 00-01-02-03   D              W
>     RPM
>
> The rpm boundary numbers stock (These go on the lines between the boxes)
> 1000,1200,2000.
> The flow boundary numbers stock, 14 grm/sec, 22,34.
> These are the block learn memory cells.
> The fuel settings are "Initial fuel*(BLM/128) = adjusted fuel.  This is as
> BL takes fuel out (Lower number) or adds
> fuel (Higher number)
>
> I would not really suggest messing with the maf calibration tables much if
> you can avoid it.  I have done some small adjustments
> in the first table to add about 10% (Below 30 grams/sec) to compensate for
> the ported maf in my car.  Other than that I have the
> injector constant set stock and run about 50 lbs fuel pressure(With vacuum
> line off) at idle.  This seems to keep the BL and INT
> close to 128 at all areas.
> At all times the maf is used to calculate the correct amount of fuel, this
> is closed loop and open loop.  There are tables to add fuel in open loop
> I have never messed with these.  The only fuel table I mess with is PE vs
> RPM.  This allows me to command a richer afr when in pe and the 02 sensor
is
> ignored.  Diacom says I am commanding about 12.0 to one at WOT, I know
it's
> not really that rich, but then I am maxing out the MAF (255 grms/sec) at
> about 4700 rpm's.
>
>
>
> Question 2.
> I just bought GMEPro and it looks really cool.  I understand the basics
but
> need to gain more knowledge.  I had posted a question about block learn
> cells 0-15 and what in GMEPro controls the amount of fuel the ECM starts
out
> with.  I also want to know how to control open loop idle so when I build
the
> Superrammed 383 with 30 pound injectors I can make the car idle.
>
> Response to question 2.
> See response to question 1.  Reset the injector constant, I would set both
> the single fire and double fire to whatever size injector you are using).
>
> Question 3.
> For instance:  I have the GMEPro software.  There are 6 MAF tables and a
> scalar for each table.  What do these affect?  It seems by changing the
> scalar you can affect the entire table.  The constants are listed as
counts.
> Counts?  What is meant by counts?
>
> Second, Say when I build my 383 and install 30 lb injectors.  My closed
open
> loop idle will be way rich.  How do I reduce BPW at idle with the bigger
> injectors?
>
> Response to question 3.  See response to question 1 & 2.  If you reset the
> injector constant to 309 lb/hr injectors.  The ecm will
> calculate the correct injector pw at idle.
>
> BTW what trans are you using?  I have done hundreds of proms getting my
355
> cu in, superram/ 6sp vet dialed in.
> I may be able to help more.
>
>
>
>
> Mark Romans
>
> ICQ#66838770
>
> Chicks dig scars.
> Pain is temporary.
> Glory is Forever.
>
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