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Air Flow Meter vs Map Sensor

Tosh

By Tosh,
in General Automotive Discussion

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Tosh Grand Master

Tosh

Posted
Posted

I'm wondering about the pro's and con's of both of these funky lil devices :D

To me it seems the MAP sensor is pereferred as seen from big HP cars in both Japan and Australia. So then why would the manufacturers stick to the AFM?? is it cost effectiveness??? Can anyone shed some light on this topic????

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kjb_r33 Experienced

kjb_r33

Posted
Posted

Air flow meter compensates for things like differing engine capacities, because its actually measuring the amount of air entering the engine. Problems with air meters is if you have an air leak, you have unmetered air entering engine, so therefore you will run lean. MAP sensors actually measure manifold pressure, so air leaks arent a real issue, BUT, there is no compensation for engine wear, engine capacity increases and so on. Air flow meters are the better of the 2, which is why most manufacturers that have used MAP sensors in the past have all gone back to air flow meters...

Roy Grand Master

Roy

Posted
Posted

As i understand it airflow meters (hot wire type aka Nissan, not those by mitsubishi or mx5) are a more accurate way of controlling the combustion cycle, whereby ensuring cleaner emmisions. Also i think airflow meters are a little more flexible when some boost, exhaust etc are thrown at them (ie dont require re-mapping). I think they are also more advanced than a MAP sensor from an ECU aspect.

MAP sensing cannot match the airlow meters for controlling mixtures, and in theory does not place any type of orifice (restriction) in front of the throttle body. If i recall correctly MAP sensors wont run engines that use high overlap (big cams), well at least wont let them idle properly. Instead they idle much higher due to the constant pressure fluctuations read by the MAP sensor.

I think the solution is using a large enough hot wire type air flow meter so not to pose a restriction on the inlet, combined with an ECU that i flexible enough to be tuned readily (ie Laptop like MAP based ECUs).

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