Originally Posted By: Scott_Tucker
Originally Posted By: QuadDriver
the MAP must be part of what I call the 'trinity' to work: tach, TPS and MAP. And general knowledge of the true adibiatic efficiency of the motor at all RPMs.
Can you please explain this?
sure, adibiatic eff. is also known as volumetric efficiency. given an RPM, thottle opening and pressure at the manifold, the engine will draw in some %age of its volume, of air.
you do tons of dyno testing to come up with the VE curve for any motor at various throttle setting, i.e. at 2krpm just toughing the gas you want a different amount of fuel vs if you are at 2krpm and stab the gas withing to accelerate.
A MAP system is only as good as the testing done before hand. and MAP systems are not tolerant more than a few % VE change before the answer they give the injectors is just plain wrong.
MAF will always be superior because it is an exact measurement of the air drawn in and uses the TPS to decide 'are we steady state or accelerating or decel?'
If you had MAP fords and wanted to make changes, the first thing you did was do the MAF conversion. GM flipped back and forth (as did MOPAR) so an engine hardware change neccessitated an ECM remap - which unless you have access to real good dynos and exhaust gas analysis, is real hard to do.
A MAP sensor is way cheaper than a MAF sensor, so that also drives the economics of the choice.
My preference should be clear.
