J N's MiniRam backfire

[Bruce Plecan]

> The recording is a neutral blip.  It also does it in gear.  Smoothly
> increasing the throttle is fine.  It's when you shift and then hit the
next
> gear kinda hard you feel a dead shot and sometimes a backfire.  Another
> interesting note is that the zero O2 reading after hitting the gas was
also
> recorded (not noticed) when I had the Super Ram on.

That's what I was saying about intake tract changes.
Also, lots of things go unnoticed / unfelt.
Generally takes a really sharpe driver to notice .1 sec events.

 There are alot of
> Minirammed MAF cars out there running fine.  Maybe someday I'll go to a
MAP
> (which by the way, TPIS claims are a real bear with a miniram) but not
until
> I learn this MAF system better.

Ya,
so is running 13s with a cross fire, but when mine was done it was about as
close to perfect as one could get.
With the MAP you can see the fuel VE table and move it around.
How good are you at moving the MAF scalers and stuff?.
Without having full or as close to full as tuning available you'll be just
patching things to work, IMO.

It just seems like your tackling so much here.
Maybe a archive search and looking for MAF would help maybe writting Mark
Romans, and ask him about how much time he has in his calibration, for a
hotrod the MAFs ar just so much work, and unless you can correct the inherit
weaknesses in that MAF, I just wish you luck.
BTW, with MAF on the GN I'm not anti-MAF, just I realise the intacke tract
is 4' long  (est), and expect a less than snappy neutral blip, and with an
auto can bypass the shift problem since it is a no lift deal
Bruce
>
> Jason
> ----- Original Message -----
> From: "Bruce Plecan" <nacelp at bright.net>
> To: <gmecm at diy-efi.org>
> Sent: Thursday, November 09, 2000 10:28 AM
> Subject: Re: J N's MiniRam backfire
>
>
> >
> >
> > (reference a modified engine)
> > Well, might be time for a 730, and MAP.
> > I'm kinda assuming that is a *neutral* blip of the pedal.
> > On a MAF system if you want any real response in neutral you just won't
> find
> > it.  They aren't made to operate that way, and the calibration is going
to
> > take a really serious amount of work to cure it **correctly**.   The MAF
> > demands a min certain lenght to get the air *straightened* out enough so
> > that the MAF sees it correctly, with the change in runners and plenum,
he
> > now has a very different system.  The AE, and IAC stuff will all have to
> be
> > retuned.   EFI like anything else must be balanced, each and every
> > component.
> > Being able to blip the gas isn't part of the EPA cycle and I doubt any
> > meaning ful time is devoted to it.  There just isn't a MAP AE
correction,
> > and the TPS AE of the MAF just would have a hard time (as in really
> > couldn't) cover that same hole.
> > Even a MAP system for a neutral blip aint the greatest in the wold when
> > comparing to say a carb..  It's the ingear stuff that matters,
> > Bruce
> >
> >
> >
> >
> >
> > > Jason sent me an XLS spreadsheet with data from a scantool that shows
a
> > > backfire happening when he blips the throttle.  Car = 1987 Vette w/
> > MiniRam.
> > >  Its pretty interesting.  (Jason, I am posting here because I can't
find
> > > your e-mail, thirdgen appears to be down, and I also want to share
this
> > > info with others here).
> > >
> > > The data clearly shows Jason 'blipping' the throttle from off idle.
> There
> > > are 4 data points on the throttle blip and you can clearly see the O2
> > volts
> > > going from the switching behavior at idle (TPS=0.53V) to 0mV on a
> Throttle
> > > blip.  The data is below.  This appears to be a fueling issue
> (expecially
> > > when viewing the SA in relation to the throttle blip and LV8).  Its
> > undetermined
> > > as to whether or not it is a PROM fueling issue or a mechanical
fueling
> > > issue.  What do you guys think?
> > >
> > > RPMs,TPS, O2, AFR, Knock, SA, LV8
> > > 875, 0.530, 836, 14.7, 0, 25.4, 57
> > > 875, 1.630, 712, 11.7, 0,13.8, 189
> > > 875, 3.310, 292, 11.7, 0,15.9, 177
> > > 1300, 2.94, 0, 11.8, 0, 28.2, 175
> > > 1725, 0.90, 13 ,14.7, 0, 45.5, 124
> > >
> > > Jason - quick question for you.  The MiniRam has ZERO provisions for
> EGR.
> > >  What PROM are you running?  Are you running $6E code, $32B code?  Is
> your
> > > PROM image based off an original TPIS image or did you start with the
> > stock
> > > image as a base?
> > >
> > > A separate issue is that IMHO, knock -should- be detected and isn't.
> > >
> > > Tim
> >
>
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