J N's MiniRam backfire

Thu Nov 9 19:29:47 GMT 2000

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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>> >>
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