MAF and 89 Vet stuff

[Romans, Mark]

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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