Fw: Miniram Backfire Update II

[JN]

I was booted from the list so if were any responses can someone forward them
to me?

Thank you,
Jason
----- Original Message -----
From: "JN" <jwn at sgi.net>
To: <gmecm at diy-efi.org>; "Romans, Mark" <romans at starstream.net>; "Walter
Sherwin" <wsherwin at home.com>; <timsiford at hushmail.com>
Sent: Monday, November 13, 2000 9:20 AM
Subject: Miniram Backfire Update II


> Good Morning,
>
>     I have worked and worked this weekend to chase this problem burning
over
> 12 chips in one day.  First I have basic question before I go any further.
> Do you have to clear the ECM (disconnect the battery) every time you
change
> the chip?   Anyway, the only table GMEPro has for Acceleration fuel is:
> AE fuel vs change in LV8
> AE fuel vs coolant temp
> AE fuel decay rate
>
> I have been fooling with the first one.  I popped in the new 30 pound
> injectors and set the constant to 33lbs for double and single fire modes.
> At idle I was a little rich with 45 psi (vacuum line off) at the rail.
> Block learns at about 110.  Pulse widths at 1.3 or so at 800 RPM.  Anyway,
> the stock values for this table are:
> LV8            Factor
> 0                .125
> 64              .125
> 128            .156
> 192            .203
> 256            .203
>
>     I increased these numbers by 25%, 50% etc, until I just jammed the
> maximum allowed (.99) in the first 3 slots (0,64,128) just to see what
> happened.  Well that was too rich or course but at least it didn't
backfire.
> I backed them down to .750 and then I get the hesitation again.  I tried
> values in between but when I cover the initial opening, it created a whole
> other problem.  The problem is two fold.  First during initial opening,
the
> flat lean condition is covered but as you keep the throttle moving down,
it
> hits PE (50% TPS) and BIG TIME richness!  Motor runs like crap and black
> smokes.  Second,  and this one is interesting.  Advance the throttle in
say
> 4th to say 1.75 volts,  O2 volts stay up and no lean condition.  All of a

> sudden, while keeping the throttle in a fixed position, the AE seems to
> decay out and it goes way, way lean and backfires to beat hell.  Why?
Well
> while in AE mode the ECM is yanking fuel out like crazy because its rich.
> After the AE decays, the Block learn is like 108 and the INT climbs
skyward
> to try and add fuel and within a few seconds it gets enough in there to
stop
> the backfiring.  ????????
>
> So it seems I need a table that is TPS related and not LV8 related.  Just
> like this car needs and accelerator pump.  Does Tunercat have a table like
> this?  I was also thinking of decaying the AE much faster so as to not
> affect the fuel trims so drastically.  Any thoughts or suggestions?
>
> Thanks,
> Jason Norris
>
>
> ----- Original Message -----
> From: <timsiford at hushmail.com>
> To: "Walter Sherwin" <wsherwin at home.com>; "JN" <jwn at sgi.net>
> Sent: Sunday, November 12, 2000 8:27 AM
> Subject: Re: New Spreadsheet
>
>
> > I absolutely agree.
> >
> > The only other idea that just got mentioned on the list (but I have also
> > been thinking of) is changing the delta TPS that is needed to enter PE
> mode.
> >  What do you think Walt?
> >
> > Tim
> >
> > At Fri, 10 Nov 2000 17:31:24 -0800, "Walter Sherwin" <wsherwin at home.com>
> > wrote:
> >
> > >
> > >To me it looks like the throttle gets opened suddenly, the mixture
falls
> > >flat on its face, and she probably backfires as a result?  I'd guess
> > >and say
> > >that a whole bunch more initial tip-in AE fuel is needed.
> > >
> > >I'm not sure what you have at your disposal in your MAF cal,  but I
> > >know
> > >that in the MAP stuff I play with there are usually two components of
> > >AE
> > >fuel, each with their own set of tables and modifiers.  The first
> component
> > >is TPS based, and gets dumped in right away to cover the initial bog
> > >hole.
> > >The second part is MAP based and gets blended in as the TPS based stuff
> > >decays away.
> > >
> > >I'd say you need much more "TPS" type AE fuel.
> > >
> > >The secondary ignition system is in good working condition right?
> > >
> > >Take Care;
> > >Walt.
> > >
> > >
> > >
> > >----- Original Message -----
> > >From: <timsiford at hushmail.com>
> > >To: "JN" <jwn at sgi.net>
> > >Cc: <wsherwin at home.com>
> > >Sent: Friday, November 10, 2000 7:16 AM
> > >Subject: Re: New Spreadsheet
> > >
> > >
> > >> JN,
> > >>
> > >> This new spreadsheet is very interesting.  I have highlighted a few
> > >sections
> > >> in ORANGE.  These sections show you opening the throttle and the O2
> > >volts
> > >> going down to zero indicating a lean condition.  You said that you
> > >have
> > >> modified the pump shot.  Which table are you referring to?  Are you
> > >using
> > >> TunerCat?  What ECM definition file are you using with TunerCat?
> > >If you
> > >> want - you can always send your BIN to me and I'll take a quick look
> > >at
> > >> it.  I CC'd Walter on this one because he was interested in your
first
> > >XLS
> > >> file.
> > >>
> > >> Tim
> > >>
> > >>
> > >> At Fri, 10 Nov 2000 09:59:47 -0500, "JN" <jwn at sgi.net> wrote:
> > >>
> > >> >
> > >> >
> > >> >Tim,
> > >> >
> > >> >    Take a look at this new spread sheet. At the bottom there is
> > >a
> > >recording
> > >> >where the backfire happened.  Get a load of the O2 volts.
Interesting
> > >> >huh?
> > >> >
> > >> >Jason
> > >> >
> > >> >
> > >
>
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