POST UPDATED IN May, 2023
Manifold Absolute Pressure (MAP)
If your vehicle uses an injection system, it has a Manifold Absolute Pressure Sensor. This sensor has the ability to measure the air pressure going to the intake manifold of the engine. Learn more about this electronic part, what the MAP sensor does, how it works, its location, and common failures.
What is the Manifold Absolute Pressure (MAP)
The MAP Sensor is a component that is responsible for quantifying the airflow that passes into the engine. This task is necessary to calculate the amount of fuel required by the engine for proper ignition. In milliseconds, the manifold absolute pressure sensor sends a signal to the electronic control unit, thus determining the ignition timing or fuel injection.
The Manifold Absolute Pressure Sensor is small in size and has no moving parts, it measures how much fuel it sends to each injector. It works in conjunction with the Crankshaft Position Sensor. This signal is received by the vehicle’s computer so that the ignition process occurs without any problem.
What is the MAP Sensor used for?
The function of the MAP sensor is to evaluate how much barometric pressure is in the environment. This information is then sent to the vehicle’s computer. Then, other operating variables are measured, such as the fuel injection speed, which makes the vehicle run without fuel failures.
The function of the MAP sensor is important, because, although your vehicle can continue circulating with a defective sensor, it will be more polluting due to the emissions it generates. Likewise, engine performance will be compromised. Engine wear is evidenced by engine detonations and stops.
How does the MAP Sensor work?
What the MAP sensor does is compare the pressure of the atmosphere to the car’s intake manifold. It then generates a signal of how much voltage is present and sends it to the vehicle’s internal computer. In turn, the computer analyzes other internal parameters and decides if more fuel needs to be injected.
When the vehicle is idle or with low air pressure, the computer sends less fuel. Otherwise, more fuel is injected into the engine for optimum performance. This action is made possible by the Manifold Absolute Pressure Sensor.
Types of MAP sensors
As for the Manifold Absolute Pressure sensor, you should know that there are two different types: frequency change and voltage variation.
MAP sensor by frequency change
This type of sensor measures the absolute pressure in the engine and the barometric pressure (when the car is off). It thus determines the amount of air in the manifold.
MAP sensor by voltage variation
This sensor does this by measuring the vacuum produced by the engine cylinders. This vacuum in turn is what produces resistance in the sensor and in turn, is what sends the signal to the control unit.
Common Manifold Absolute Pressure Sensor Failures
Learn about some of the faults that can occur in the MAP Sensor and how they can affect your vehicle:
Check Engine Light On
This may be the most obvious indication that the MAP is faulty. This means that the computer sends a malfunction diagnosis so that the Check Engine Light on the dash comes on. A scanner should be used to read the codes to determine what type of malfunction it is.
However, other problems can cause the light to illuminate on the dash panel. For example, an improperly connected port or a leak in the vacuum hose. Therefore, before replacing the MAP sensor, check the reason for the warning.
Increased pollution
If you live in a country where an emissions test is required and your MAP Sensor is faulty, you may be in for a surprise, the result may show an increase in pollutant emissions. If other faults have already been ruled out, the cause is the Manifold Absolute Pressure Sensor.
Engine Performance Problems
This fault is evidenced by a pressure imbalance and may be due to the sensor sending the wrong signals to the ECU. Then, when you accelerate or decelerate the vehicle, you will feel that the engine is not running well. Even in an idle position, the vehicle keeps accelerating.
Lack of spark plug maintenance
Fouled spark plugs can become contaminated to such a degree that they result in inefficient combustion. The result can be an engine that runs weak due to a drop in power. Therefore, take care of your spark plugs so as not to affect the performance of the sensor.
Increased engine pressure
Sometimes, the failure occurs when you accelerate the vehicle and it is slow to respond. On the contrary, it accelerates suddenly for no apparent reason. These two actions are common signs of problems with the MAP sensor.
OBD2 codes concerning MAP sensor
If the MAP sensor is faulty under the scanner it may give the code P0107. The meaning of this number is explained in a low voltage input to the engine control unit or ECU. Typically, the value is less than 5 volts, a range that is below for good engine performance. Other fault codes that can be generated by MAP Sensor problems are as follows: P0105, P0106, P0108, and P0109.
How to test if the MAP Sensor is working?
Checking the MAP Sensor requires only basic mechanical knowledge and a few tools. Get a tachometer and a portable vacuum pump and follow these steps:
- Locate the sensor in the passenger side engine compartment, you can avail yourself of the vehicle’s service manual.
- Check that the vacuum hose is clean and make sure that the wires are not loose or broken.
- Consult the service manual to find out what type of MAP sensor your vehicle has. For a frequency sensor, use a tachometer, while a voltage sensor requires a voltmeter.
- Disconnect the sensor connector and turn the ignition key without running the engine. Measure the voltage, if it fluctuates, it is indicative that it is running. Compare the voltmeter reading with the service manual to confirm.
How to clean the Manifold Absolute Pressure Sensor?
The MAP sensor is cleaned with the engine off. Disconnect the sensor and wipe the surface with a clean, dry cloth. Make sure that the hose between the sensor and the intake manifold is well coupled. If you detect breaks, the best thing to do is to replace the sensor, as the signal it sends will be defective when air enters.
It is important to remember that the MAP sensor has the function of coordinating how much air the engine receives to inject the right amount of fuel, when the sensor has problems, the engine will not respond correctly.
MAP Sensor Location
You can find it near the throttle butterfly, inside the throttle body, by the intake manifold of the car. In some vehicles, the MAP sensor is located in conjunction with the ECU. You can find out the exact location of the MAP sensor by acquiring the car’s electrical diagrams.
