Bosch MAF sensor question

[Daniel Ciobota]

Mark Romans wrote:

> Hi Bruce:  I had seen the Modern Muscle ad, went back and looked again.  The
> "MAF Translator" costs $179.00 and will allow use of the LT1/LT4 Maf on the
> L98.  They also have written a prom that allows the ecm to read up to 512
> grams/sec of air flow.  Unfortunatly I don't have the expertise to even
> attempt to re-write the 89 L98 code to read that kind of flow.  Some one
> could make some $ if the did figure it out though.

Those of us that have fooled around with ford eec-iv setups have found a fairly
easy way to compensate for increased airflow through the motor, causing the
computer to peg at max too early.  The solution is to use a larger maf housing
and proportionally larger injectors (or higher fuel pressure).

By keeping the sampling tube (the ring with the thin wires inside) constant, the
maf will read proportionally lower airflow numbers with increase in housing
size.  That's due to the air velocity through the sampling tube dropping (at
constant cfm) with the larger housing.

 To correct for the lower readings from the maf, use a proportionally larger
injector (or higher regulator pressure).  The computer thinks at this point that
the motor is flowing less air that actual, but because of the larger injectors
(or fuel pressure) is actually delivering the correct amount of fuel.

 I wish the ford maf units could work on the L98 motors, but alas, someone told
me that they operate differently.  All I know is that the ford maf sensor is set
up like a voltage bridge... don't know anything about the L98.  Still, if
someone could cast or machine a larger housing to accomodate the gm sensor, then
they could sell that and matched injectors as a recalibration kit.

 Btw, 24lb/hr motorsport injectors work wonderfully on those old L98 motors.  My
stock ones were 22lb/hr (89 vette motor), and after a few minor mods like
exhaust and some head work I was running a bit lean.  The new injectors and
stock fuel pressure are a perfect fit.  :-)

Daniel


>
> Mark
> -----Original Message-----
> From: CSH-HQ <nacelp at jvlnet.com>
> To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>;
> gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
> Date: Tuesday, October 19, 1999 6:11 AM
> Subject: Re: Bosch MAF sensor question
>
> >Got lots to do this am, but Modern Musle is selling a late model high flow
> >maf, and I've just read an ad or two about them, and will post the info
> >later. Of course with SD, you don't have that "problem" of sizing a MAF
> from
> >another application, and spending hours with diacom so see where to start.
> >Then there is no correlation between what diacom reads out to what the maf
> >is reading, so again I'd expect the AFR displays to be "different".
> >Unless, you change the code, and known the flow per increment of change.
> >I hope that's clear.
> >  Speaking of patches,  anyone see any 2-3 MAP versions of the ASBX
> (Holden)
> >code?. Just checking....
> >Cheers
> >Bruce
> >>
> >>Hello All:  What I hope is a quick question.  The L98 MAF reads to about
> 255
> >>grams/sec.
> >>My engine being normally aspirated hits this level of flow at about
> >>4600-4700 rpm's.  Is there a way to make a software patch that allows flow
> >>to be read to double that?  Is there a maf that will read more?  I seem to
> >>remember comment about a Bosch Porsche 928 MAF sensor.  I also remember
> >>reading somewhere about a maf doubler for the GN 3.8 Turbo engine.
> >>
> >> I have a friend who's turbo 406 is hitting the 255 grams/sec at about
> 3000
> >>rpm's at 50% throttle and 2500 rpms and 50% more throttle to go!
> >>
> >>Mark
> >>
> >