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Re: MAF and 89 Vet stuff
Dominic Sorresso wrote:
>
> I upgraded my 84 ECM to a 7747 from Turbo City. My 4+3 OD works well enough
> although not exactly as original. In the original program from TB City, it
> would not engage when flipping the switch. Later, Turbo City provided
> iterations of the chip which enabled OD operation thru switch and
> accelerator. My only real problem at this point is that the trans will drop
> out of OD at hi speed when TPS is near or at closing. Can't tell at this
> point but I would estimate about 20% TPS. However, kickdown to direct will
> happen at about 74mph. Therefore it will coastdown in OD say from 85mph with
> <20% TPS until it reaches 74 mph at which point direct gear is engaged.
> Tapping accelerator brings back OD. At low speed, OD disengages at 34mph
> with <20% TPS. OD operation was enabled with NO pin reconfiguration at ECM.
Haha. No pin reconfig, that is, after reconfig from crossfire ecm to
747. It's not like you're comparing 2 different year Vettes with
facory cals and ecms when you say this. : )
> Is there any way to remedy (eliminate) kickdown at hi speed either with
> software change or pin reconfig?
What ecm terminal is the o/d switch connected to in your car? How
about the o/d relay? These would be a clue as to what to change in
the prom. The 86-88 cars use the tcc line for o/d control.
BTW, anyone who switches to a later (auto trans) cal. in the Vette
might want to watch for an illuminated o/d light in the dash
afterward. There's no specific wire from the ecm to control that
light, I believe the instrument cluster is turning on the light based
on serial data from the ecm.
Shannen
>
> Dominic
> ----- Original Message -----
> From: "Shannen Durphey" <shannen@grolen.com>
> To: <gmecm@diy-efi.org>
> Sent: Sunday, August 13, 2000 6:52 AM
> Subject: Re: MAF and 89 Vet stuff
>
> > 89 Calibration is different, as it's for a 6 speed. There's no
> > control for the o/d unit.
> >
> > The 88 schematics are on the ftp site. IIRC, Pin C8 is O/D switch in
> > 86. In 87 they moved the O/D sw to pin c7 and put a a first gear sw.
> > in the trans which connects to pin c8. Leave c8 open and the o/d
> > operation will be the same as you're used to. You might be able to
> > use the an auto cal., use tcc tables for o/d, and use a different
> > switch for o/d control. It would be an interesting project.
> > Shannen
> >
> > J. T. Spilman wrote:
> > >
> > > I just upgraded my 4+3 85 to an 89 ECM I jumped two wires to get the O/D
> > > switch to work. What pins did you move to get the O/D to respond
> correctly?
> > >
> > > Thanks
> > > JT Spilman
> > >
> > > -----Original Message-----
> > > From: owner-gmecm@diy-efi.org [mailto:owner-gmecm@diy-efi.org]On Behalf
> > > Of Shannen Durphey
> > > Sent: Saturday, August 12, 2000 11:25 PM
> > > To: gmecm@diy-efi.org
> > > Subject: Re: MAF and 89 Vet stuff
> > >
> > > 88 4+3 is still better than 86. Requires moving one pin at ecm.
> > > Shannen
> > >
> > > Romans, Mark wrote:
> > > >
> > > > If someone has an 86 and it's an automatic I would strongly recommend
> that
> > > > they convert to 89 code because it's much better supported and runs
> better
> > > > and eliminates the cold start injector. If they have a 4+3 they are
> > > > screwed.
> > > > Mark
> > > > ----- Original Message -----
> > > > From: "TK" <terryk@foothill.net>
> > > > To: <gmecm@diy-efi.org>
> > > > Sent: Saturday, August 12, 2000 2:44 PM
> > > > Subject: Re: MAF and 89 Vet stuff
> > > >
> > > > > 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@starstream.net>
> > > > > To: <jwn@sgi.net>
> > > > > Cc: <gmecm@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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