MAP map or MAF map

[robert dingli]

Bryan writes,
> 
> 
> >> As for fuel curves, the speed density mapping is calibrated empirically.
> 
> >I love that bit - makes tuning lots easier.
> 
> What is the consensus with the diy-efi'ers out there:  do you prefer 
> manifold air pressure (MAP) sensing or mass air flow (MAF) sensing to 
> determine the air flow into the engine.  Seems to me that probability of 
> success and ease of tuning would be achieved with the MAF sensor.  It 
> measures mass flow directly, and is not affected by changes in temperature 
> or barometric pressure.  A first order approximation of the injector pulse 
> width could be made if one knows the flow rate of the injector and the mass 
> air flow.  This would make getting the engine running for the first time 
> much easier.
> 

MAF systems require inlet air temp for compensation as do MAP systems.  MAF
system also use a barometric pressure sensor for compensation while MAP
systems don't.

> Ford sells their MAF for the 5.0 liter Mustang GT for around $150.  It can 
> flow enough for at least 210 horsepower.
> 

Ford sells there MAP for around Aus$40-50 (US$30-37).  It can provide an
air flow estimate for almost any non-turbo car or bike and you still need
one for a MAF system.

Robert

-- 
----------------------------------------------------------------------
             Robert Dingli           r.dingli at ee.mu.oz.au

Power and Control Systems                 Thermodynamics Research Lab
Electrical Engineering                    Mechanical Engineering
   (+613) 344 7966                           (+613) 344 6728
  University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA
----------------------------------------------------------------------