Difference between AFM and MAF sensors?

[mulligan-can]

Whats the difference between a MAF and an AFM sensor? Furthermore I've been reading on another forum and a lot of people seem to be using MAP sensors (I think that was it...) instead.

Anyway, as these all are ways of measuring air flow what is the difference between them all?

Oh btw I've also been hearing an AFM sensor is the more accurate out of a MAP and AFM. Is there any advantage to the added accuracy?

 

[mag]

Whats the difference between a MAF and an AFM sensor? Furthermore I've been reading on another forum and a lot of people seem to be using MAP sensors (I think that was it...) instead.

Anyway, as these all are ways of measuring air flow what is the difference between them all?

Oh btw I've also been hearing an AFM sensor is the more accurate out of a MAP and AFM. Is there any advantage to the added accuracy?

MAP (Manifold Absolute Pressure) sensor.

MAP Sensor constantly measures the vacuum in the intake manifold.

AFM measures air flow in to the manifold and MAF is the basicly same as AFM as it measures Mass air flow..

 

[mag]

Whats the difference between a MAF and an AFM sensor? Furthermore I've been reading on another forum and a lot of people seem to be using MAP sensors (I think that was it...) instead.

Anyway, as these all are ways of measuring air flow what is the difference between them all?

Oh btw I've also been hearing an AFM sensor is the more accurate out of a MAP and AFM. Is there any advantage to the added accuracy?

MAP (Manifold Absolute Pressure) sensor popular for swaps as the wiring is less involved, air intake plumbing is usually heaps easy and the map sensor (around $30) is considerable cheaper than a MAF sensor ($200-$300).

MAP Sensor constantly measures the vacuum in the intake manifold.

AFM measures air flow in to the manifold and MAF is the same I think as AFM as it measures Mass air flow..

Pic of a VZ Commodore MAF. A MAP sensor and VL RB30 AFM

 

[mulligan-can]

Ok. So if your aiming for around 200rwkw would you be better sticking with the AFM or going for a MAP? (both with an aftermarket ecu :S)

 

[rb26dett]

If you get an aftermarket ECU, you dont need to run the AFM

 

[Lost_Pete]

A MAP, MAF and AFM are all used to measure the amount of air in the engine. However they do it by different methods.

A MAP (Manifold Absolute Pressure) sensor measures the vacuum or boost, in a turbo or supercharged application. The amount of air is then calculated using the volumetric efficiency of the engine and temperature of the air. In reality it is a referred to a table in the ECU program. The MAP sensor allows you to calculate the mass of air and from that you can determine the mass of fuel you need to inject. Older fuel injected cars tend to use MAP.

A MAF (Mass Air Flow) or AFM (Air Flow Meter) measure the mass or volume of air. These work in various ways including measuring the cooling effect of the air as it passes a heated element, vortex shedding. Older methods include a vane which is pushed by the air flow. There is usually some compensation for temperature. As you basically measuring the mass of air it is more direct measurement and you can easily calculate the mass of fuel required. Most if not all new cars run MAF/AFM.

Can you swap them?
Not with your standard ECU. Aftermarket ECUs may be able to use either.

Which is better?
Most high horsepower guys seem to like MAP as it eliminates a restriction in the intake path. You can also exceed the range of a MAF/AFM in big horsepower application both at the top end or at idle. From an engineer's point of view I think that the MAF/AFM is a more precise method. From an emissions and efficiency point of view a MAF/AFM is normally the better approach.

MAF/AFM Tubes
Some people sell larger diameter intakes which you transfer your MAF/AFM to. The change in tube diameter actually changes the calibration of the MAF/AFM. Basically it can make you car run leaner which under full throttle applications may improve horsepower at the risk of engine damage.

MAP to MAF Converters
These are also available which allow you to run a MAP sensor in place of your MAF/AFM sensor.

(Disclaimer: Just my 2.54cents worth)