J N's MiniRam backfire

[JN]

Tim,

    The 90 Corvette that used the speed density system had a different
radiator angle, shroud, etc.  It would be a major PITA.  Of course I like a
challenge......

Jason
----- Original Message -----
From: <timsiford at hushmail.com>
To: <gmecm at diy-efi.org>
Sent: Thursday, November 09, 2000 2:29 PM
Subject: Re: J N's MiniRam backfire


> JN,
>
> With Speed Density you just remove the MAF and use an Intake Bellows from
> a SD car.  Take a look at my webpage at
> http://www.mycar.net/mafb/registry/detail.cfm?id=101
> Pay attention to the pics of the engine bay and it'll make sense.
>
> I understand your reasoning for sticking with the stock MAF system.  Its
> not a bad idea.  They can be made to work very well.  Its just easier to
> work with MAP ;-) :-)
>
> Tim
>
> At Thu, 9 Nov 2000 13:52:34 -0500, "JN" <jwn at sgi.net> wrote:
>
> >
> >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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> >> >efi.org
> >> >>
> >> >>
> >> >
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> >> >
> >
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