Having the right air-fuel ratio is necessary for your car’s engine to function optimally. However, this is not something that you can estimate manually. You need a reading device to simplify your work.
Luckily for you, technology has caught up, and we have a mass airflow sensor device. The main role is to prevent an engine knock. Thus, it might be disastrous if your car’s sensor becomes faulty.
A fault may be caused by simple things like dust accumulation, which may contaminate the car part. But how will you know if your car’s mass airflow sensor has failed?
Well, that is what this article is about.
Below, I have explained in detail what a mass airflow sensor is. I have gone ahead to bring to your attention the main tell-tale signs of a faulty mass airflow sensor. I will also give you a snippet on how to trick a mass airflow sensor.
I hope you will find all your answers within this text!
What Is A Mass Airflow Sensor?
As already hinted above, this is a vital car part that ensures the optimal functioning of your car’s engine. Put differently, a mass airflow sensor (MAF) is a sensor that measures the mass flow rate of air that gets into the engine’s outlet.
This information will be necessary for ensuring the engine burns fuel and operates with low emissions. How does this happen? The engine control unit (ECU) takes up the information, which balances and delivers the right amount of fuel mass to the engine.
Since air density often changes depending on the temperature and pressure applied, a mass airflow sensor becomes the right candidate for measuring air mass.
Their effectiveness is top-notch as compared with volumetric flow sensors. It is necessary to measure air mass to determine the amount of fuel to add. That will help to achieve the recommended air-fuel ratio.
The recommended air to fuel ratio is 14.7 pounds of air to 1 pound of fuel (14.7:1). However, this usually varies in the real sense. For instance, accelerating may require a higher ratio (say, 12:1), while cruising may require a lower proportion (around 22:1).
There are two main kinds of mass airflow sensors. One is the vane meter sensor, and the other is the hot wire sensor.
Vane meter mass airflow sensor
It relies on a spring-loaded air vane connected to a variable resistor to operate. The vane rotates whenever there is airflow, and the rotation angle is directly proportional to the amount of airflow.
When voltage is applied to the variable resistor, the voltage reflects o the output terminal in proportion to the angle covered by the rotating vane. In a nutshell, the vane meter does not directly measure the volume or mass of air. It instead relies on the drag force of the air that flows against it.
The device is not without shortcomings. The main con is that it results in airflow restriction, which subsequently curtails the engine.
Also, its moving contacts are subject to wear off with time. It may be hard to locate the right mounting spot in a confined engine, and the sensor will have to respect the laws of gravity.
Hotwire Mass Airflow sensor
This type of sensor requires a suspended wire in the engine’s air stream to be heated through the consistent application of voltage. To operate, it relies on Ohm’s law.
As its temperature rises, its electrical resistance also increases, and this causes a variation of the current flowing the electrical circuit.
Conversely, the wire’s temperature decreases when air flows past it. That results in a decrease in its resistance, allowing more electrical current to flow through the electrical circuit.
The increase in the flow of current heats up the wire, and the resistance increases until it reaches equilibrium. The process repeats itself.
The increase and decrease in current help measure the mass flow of air since it is directly proportional to the amount of air passing past the hot wire. The measurement is converted into a voltage by the integrated electronic circuit, and this I what is relayed to the engine control model (ECM).
How to Trick a Mass Air Flow Sensor
For this, you will need to find a unique tube with the same attributes and shape as the car’s MAF sensor. The tube has to be metallic and not plastic. All you have to do is place it in front of the ignition source.
Once it heats up, the tube will relay a reading similar to the air-fuel mixture given off by your car’s tailpipe. That tricks the sensor into thinking that you are using more air. This method relies on the sensor’s high sensitivity to heat.
Can You Bypass The Mass Airflow Sensor?
You can use your car without the MAF sensor, although I wouldn’t advocate for that. Although the car will still run, it won’t be half as efficient as it ought to be if you have a MAF sensor.
That can be attested by manufacturers creating a backup functionality dubbed ‘lookup table’ to ensure that your car will not run into problems on the road once the MAF sensor stops working. It prompts the engine control model to look at data from different sensors such as the air temperature sensor or the engine RPM when it fails.
However, the vehicle still does not run optimally when using this functionality.
You can also bypass the MAF sensor by tricking it using a similar tube as explained above. For emphasis, this won’t guarantee optimal engine performance and may even cause further problems to your vehicle. I recommend getting your MAF sensor fixed rather than bypassing it.
Signs and Symptoms of Bad Mass Air Flow Sensor
A malfunctioning mass airflow sensor can cause critical problems for our car since the fuel injection will be calculated incorrectly by the engine control model. As a point in case, it is likely to result in poor combustion hence high amounts of toxic carbon monoxide, leading to a lean engine.
Alternatively, it may result in wastage of fuel since some escapes from the exhaust unburned, low engine performance, and more emissions of harmful gases. It becomes important to notice when your sensor has become faulty to avoid these adverse consequences.
Here are the main signs of a bad mass airflow sensor.
Hard to start the vehicle
If you are having trouble starting the car, this might signify that your mass airflow sensor is bad. It happens because your car engine needs a lot of fuel to start. When the sensor is bad, the engine control model is prevented from providing enough fuel injection necessary to start the engine.
Dark exhaust smoke
A faulty mass airflow sensor prevents effective combustion, and as such, you are likely to see a dark black smoke escaping from the car’s exhaust system.
A faulty MAF sensor limits the injection by ECM, limiting the ability to accelerate while on the highway or when cruising down a road.
Check engine light turns on
When the illuminated check engine light turns on, it might be a red flag that your MAF sensor has gone bad. That is a warning light found on the car’s dashboard. It might be indicative of a circuit diagnostic trouble code.
Poor fuel efficiency
Too much fuel consumption is another major symptom of a damaged MAF sensor. A faulty sensor hinders effective fuel consumption, meaning that some fuel escapes without being burned. That leads to poor fuel efficiency.
Surging and hesitation
When the MAF sensors are not functioning, there is unusual power surging and, in most cases, hesitation when you try to accelerate or cruise.
Hi I’m Marshall based in 1478 Doctors Drive Santa Monica, CA. I’m your DIY Car Repairman with more than 5 years experience in automobile repair, a skill I learned from my old man.
I started this blog to share my experience on both simple and technical aspects of your car.