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What is a Air flow meter


Air mass meters are also commonly referred to as air flow meters, Maf sensors and airflow meters. They measure the mass of the air flowing into the engine.  The air mass information is necessary to calculate and deliver the right amount of fuel to the engine.

A mass air flow sensor is used to find out the mass of air entering a fuel-injected internal combustion engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude and use of a turbocharger and this is an ideal application for a mass sensor.

Mass air flow sensors don’t employ technology that measures air mass directly. However, with an additional sensor or two, the engine’s air mass flow rate can be accurately determined.

Air Flow Meters are a common problems


Air Flow Meters are a common problem

Air Flow Meters measure the amount of air passing into the engine from which the computer can work out how much fuel to add to get the perfect mixture for that specific throttle opening; the computer does this by referring to a map in its memory.

The Air Flow Meter works by seeing how much current it takes to keep a wire at a specific temperature.

However it is a sensitive instrument and it can be contaminated by oil (often used in aftermarket performance air filters), damaged by excess vibration caused by broken air through which contamination gets in, minute particles of dust and pollen etc, because of this contamination, the voltage will read less thus giving the ECU the wrong voltage output, this will in turn over or under fuel the engine making the car harder to start, the tick over will be lower this will in turn make the car stall, use more fuel, and give lower performance.

How to check Oxygen sensor is damage or replace


To check for a damage or worn out oxygen sensor or replace :

Remove the o2 sensor and carefully inspect it

The Picture below is how a damage 02 sensor, oxygen sensor should look

Damage o2 sensor

Once you removed the old oxygen sensor you will want to follow the directions in the Bosch Universal Oxygen Sensor Kit. The directions clearly tell you how to connect the old oxygen sensors male connector that you cut loose, to the new sensor. Once you have done this if you ever need to replace the oxygen sensor again you won’t have to cut on any of the wires in the car. You’ll have a new (second) connector between the male you cut loose and the oxygen sensor.

Tools used for o2 sensor, oxygen sensor

After you’ve finished with the BOSCH kit instructions you should apply more anti-seize to the threads of the new o2 sensor, oxygen sensor. Now just simply install everything in reverse order.

Once you have the car put back together and you start it up you might find the code is still present. Have someone with a Computer reset it for you. If you find even after clearing the code that it comes back you might need to have your ECM flashed/updated by the dealer or diagnostic place at this point.

Airflow meter fault symptoms


Also sometimes known as, Air Mass Meter, MAF, Air Mass Sensor, Mass Air Flow, Air Flow Meter, AFM etc

It is the device used in many fuel injected engines to measure the amount of air entering the engine so the computer can control the air/fuel mixture. Located ahead of the throttle body, the MAF sensor uses a heated wire or filament to measure airflow. Typically air flow sensors can go fault every 40,000 miles, this is due them getting clogged up with dirt within the induction system. They are very easy to replace, normally just remove two screws and replace the unit.

Some common symptoms of a faulty air flow sensor:

* Reduced drivability, cutting out when the engine speed drops (approaching bends etc)
* Loss of Power, turbo lag on turbo applications
* Excessive Black Smoke on diesel applications
* Reduced fuel economy and lumpy running
* Can feel like you are hitting a brick wall like a rev limiter etc

A diagnostic machine such as a VAG-COM will sometimes point out the Air flow meter is faulty, however not always. Some cars may also get an engine management warning light on your dashboard.

On most vehicles it’s possible to test if your mass air flow sensor is faulty, simply by disconnecting the harness wire which is going into it. If then you go out for a SHORT drive in your vehicle and most of the problems you were having before are gone, then this will mean that it needs replacing with a new unit. Its certainty not advisable to drive your car for long periods of time with the MAF disconnected as premature engine damage and reduced fuel economy may occur

Replacing a faulty Air flow sensor will certainly pay for itself with the increased fuel economy you will get and curetoo many of the problems listed above.

The air flow meters will occasionally fail completely which will bring up a light on the dash and the symptoms described here are only the usual ones as we have known the fault to become apparent in other ways. Beware however as Lambda (or Oxygen) sensors in the exhaust can also give very similar symptoms to Air Flow Meters.

The easiest way to check if the Air flow meter is faulty is to unplug the wiring loom, start the car, if the car runs better then you have a airflow meter problem, its that easy, but do not drive the car like this it will cause you other problems, it can burn out the Lambda sensor and the catalytic converter (very expensive to replace).