Running a MAF Sensor Switchover to MAP

[mapper]

is it possible to use the MAF signal as a load input? And maybe do a switchover to MAP on positive pressure?

The reason i ask: I feel that MAF is more accurate on low load areas. I feel also if you do the charge temperature estimation correct, idle and low load are not that precise than with a MAF system. 

I have to do a EURO 3 emission standart test, where exact and stable AFR's are a essential prerequisite to pass the test. 

http://en.wikipedia.org/wiki/European_emission_standards 

[Simon]

You can set it as the load input but really it does not work that well on our units.

This is only due to the firmware being totally targeted at MAP as the main load input.

[Davidv]

Hey,

Just to share some experiences.

My preconception was that there would be a noticable difference between MAF and MAP, at low load/cruising etc.

I got my car running with a MAP sensor first, then setup a new table as MAF also.

To be honest when I datalogged both, I didnt see any areas of finer resolution with the MAF.

The only notable area of difference I could see is when you slam the throttle shut, the MAF sensor will show a steady reading of air while the RPM drops, but the MAP sensor will show a lower vaccum at higher RPM and then vaccum decreasing slightly as the RPM drops.

But if you've got decel fuel cut turned on, that's an area where there's zero fuel going in anyway.

Having the MAF sensor connected (datlogging only) was super handy for tuning VVTI angles at WOT and a few other things, but in terms of how the car runs after trying out both I wouldnt be able to pick the difference in a blind test.

A MAF sensor might show an advantage if you've got a ram air type setup, and barometric pressure correction comes from the ECU rather than the area of varying pressure that the engine is drawing the air from. (Very minor difference)

But again if you've got closed loop + a wideband this will be compensated for regardless, in terms of your emissions.

In the end my conclusion was that the MAF sensor is not worth the headache of calibrating, and then reliability issues if you end up getting an air intake leak etc that throws off all of the readings.