I was wondering why did honda change from map to maf since they introduced the civic in 2006

 

I thought it had to do with emissions and the EPA. I've heard it's a more accurate way for the computer to determine the gr/sec of air entering the motor so it can then be more accurate in fueling the motor and provide optimum air/fuel ratios for performance and economy.

 

that would make sense

 

Actually, they switched because the engine changed from an Otto cycle to an Atkinson cycle engine, which makes a MAP sensor somewhat useless during light load conditions (when it runs in Atkinson cycle mode).

 

and what does it mean ?!

 

 

MAP systems calculate the air flow indirectly. They are used because they are cheaper than the factory MAF sensor. This is a programming time for them against the recurrent costs of pricy MAF sensors. The MAP system has a lot of maps of fuel and power, the MAF team, but calculates air flow based on sensor input RPM, throttle position, the engine operating temperature, the temperature of intake air, atmospheric pressure and, above all, the manifold pressure..

 

Google is a powerful tool.

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

http://asia.vtec.net/Engines/RiVTEC/index.html

 

Your post doesn't make a lot of sense.

First off, the MAF sensors doesn't read manifold pressure, that's what the MAP sensor does!

The MAF sensor contains a little wire that is heated and tries to maintain a certain temperature. When air passes over the wire it cools the wire. The amount of voltage the ECU has to send to the wire to maintain the temperature is how it determines the grams/second of air entering the motor.

A MAF sensor can't read pressure so that's why using the MAP sensor can be easier for fuel tuning on forced induction. The ECU knows the volume of the intake manifold, so if it knows how much pressure is in the intake manifold it can calculate the amount of air entering the engine and then fuel properly.