J N's MiniRam backfire

[JN]

TS,
Yes I agree with you on the logic with the 30 pound injectors.  I might try
them to eliminate the possibility of faulty stock injectors.  As far as
converting to a 730, there are other issues for me.  First I have to buy the
equipment.  Then I have to learn how to convert it over.  Finally I have to
start from square one and learn how to tune MAP systems.  I just don't want
to tackle that now.  If I learn it I probably would like it better since
that is a general consensus.  Then there is the physical intake tract.  Do I
just leave the MAF dead in there?  Isn't part of the benefit of a speed
density system to loose the restriction of the MAF?  I'm asking (read I'm
not trying to be sarcastic).

Thanks again for the help.

Jason


----- Original Message -----
From: <timsiford at hushmail.com>
To: <gmecm at diy-efi.org>
Sent: Thursday, November 09, 2000 12:10 PM
Subject: Re: J N's MiniRam backfire


> JN,
>
> Yes, there are many MiniRammed MAF cars running absolutely fine.  The
system
> will work.  The 730 is just slightly easier to Tune IMHO and other's
opinions.
>  But, you can make the MAF system work ... it will just require a little
> more time and experimentation.
>
> I would begin with those 30lb injectors.  Are they new injectors?  The
reason
> that I am suggesting this is because if the 30s are new then this would
> rule out a MECHANICAL injector problem.  Plus - with the MiniRam it only
> takes about 1/2 hour to swap injectors.  Then, put the fuel pressure at
> around 44 and burn a new PROM with the injector constants set to 33lb/hr.
>  Now, I know I am comparing apples to ... hmm ... pears, but my 730
MiniRam
> system runs great with the 30's.  The 30's should not be too big.  There
> are plenty of MAF cars running 30's.
>
> If you still have the backfire once the 30s are installed (which should
> happen if this is not an injector issue) then I would play with the Fuel
> Pressure just to see if you can make the situation go away by INCREASING
> the fuel pressure.  NOTE: I AM ONLY SUGGESTING THIS AS A QUICK AND DIRTY
> METHOD FOR DETERMINING IF THIS PROBLEM IS FUEL RELATED.  If the problem
> did go away then you would NOT want to keep the pressure up that high.
> This will fook up your BLMs everywhere and you run the possibility of
going
> lean in the upper RPMs if your fuel pump can't supply enough fuel at that
> pressure.  This will just tell you if it is a fuel issue.  If the problem
> goes away then you want to put the FP back to normal and begin playing
with
> the fuel curves to make the situation go away.
>
> Tim
>
> At Thu, 9 Nov 2000 11:09:54 -0500, "JN" <jwn at sgi.net> wrote:
>
> >
> >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.  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.
> >
> >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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