FW: MAF Upgrad

[Joe Boucher]

As I understand the original problem, the stock 350 Corvette MAF ecu has a one
(bit?) byte register (correct nomenclature?) for air flow.  This means the byte
has a maximum value of 255.  For that MAF, this means enough air for about 325
HP.  (What does a ZL-1 use?  MAF or MAP?  What MAF?) If you flow more than that
through the MAF, the ecu still interpretes this as 255.  If you can find the
maps in the prom that control the injector pulse vs the MAF then you can change
injectors and reprogram the look up table.  Except you'll still hit that 255
value.

I, and Mr Thompson, was thinking of bypassing the MAF with a tube to pull more
air into the engine and using the MAF to measure one tube and reprogram the
prom, using bigger injectors and assming more air and more HP.  But this add on
box has given me another idea.  Install two MAF's feeding the throttle plate.
Take the signal from both MAF's and add them with the box.  The box takes the
two values, looks at the lookup table and outputs a value to the ecu within the
0 to 255 value.  Reprogram the lookup table to match the new MAF and injector
sizes.  The rest of the system and operating software stays stock.  From what
John Bucknell has said, the MAF is more sensitive at lower flow rates than
higher rates.  Both MAF's would be operating in the lower, more sensitive
regions.

Whatayathink?  Uh? Uh?

Joe Boucher
'70 RS/SS Camaro  '81 TBI Suburban

Bill Eubank wrote:

> Well, why not put a little box between the sensor and the ECU?  The little
> box would intercept the MAF signal and output another signal based on a
> lookup table.  The advantage here is that you need to change little of your
> stock setup.
>
> I do microcontroller hardware and software design for a living.  So I would
> use a micro that has and A/D and EEPROM for nonvolatile table storage.  The
> analog output could be done with a D/A converter ...  The lookup table
> calibration would be done with PC (or laptop) connected with a serial cable
> to the little box.
>
> I may want to take this on as a side project if there?s interest ...
>
> Hacker Bill
> eubank at tc.umn.edu
>
> >  In order for a bypass to work,
> > you must have roughly the same pressure drop ratio at low flow to high
> > flow as the MAF alone (as pressure ratio is related to flow).  Flow
> > bench would tell you easy.  Little differences should be handled by
> the
> > HEGO.
> > ---------------------- Forwarded by John R Bucknell/JTE/Chrysler on
> > 02/26/98 03:02 PM ---------------------------
> >