Where is manifold absolute pressure sensor

Typically found in fuel injected engines, the manifold absolute pressure MAP sensor is one of the sensors an engine control module ECM uses to calculate fuel injection for optimal air-fuel ratio by continuously monitoring intake manifold pressure information.

The MAP sensor also provides a vital role in helping the ECM determine when the ignition should occur under varying engine load conditions. Whichever sensor your engine uses, the ECM will not be able to optimize fuel injection without accurate air mass information from a working sensor. And poor air-fuel ratio at the very least will cause performance issues and premature engine wear. A MAP sensor failure can be difficult to diagnose, but with the help from Delphi Technologies, we can explain what causes it, what to look out for, and how to replace it if it fails.

The MAP sensor is typically located on the intake manifold, either next to or on the throttle body itself. On a forced-induction engine, the MAP sensor can be found on the intake tract before the turbo. Inside the MAP sensor is a sealed chamber that either has a vacuum or a controlled pressure that is calibrated for the engine. Dividing the sensor vacuum and the vacuum from the intake manifold is a flexible silicon wafer a. When you start the engine, pressure in the intake manifold decreases creating a vacuum that is applied to the MAP sensor.

When you press on the gas accelerator pedal, the pressure in the intake manifold increases, resulting in less vacuum. The differences in pressure will flex the chip upward into the sealed chamber, causing a resistance change to the voltage, which in turn tells the ECU to inject more fuel into the engine. When the accelerator pedal is released, the pressure in the intake manifold decreases, flexing the clip back to its idle state.

Like most electric sensors, MAP sensors are sensitive to contamination. If the map sensor uses a hose, the hose can become clogged or leak and unable to read pressure changes. In some cases, extreme vibrations from driving can loosen its connections and cause external damage.

Electrical connectors can also melt or crack from overheating due to close proximity to the engine. In either of these scenarios, the MAP sensor will need to be replaced.

MAP can be located in the engine compartment as a separate component or integrated in the onboard controller. Appearance Fig. Converter transforms the measured pressure into an electrical signal which is fed into the onboard controller. This method is based on the theory that with every turn the engine sucks fixed volume of air. Accuracy of this method can not be compared with that of the air quantity sensor, which after accurate measure of the airflow calculates the fuel mixture ratio based on mass or volume of air sucked in from the engine.

When there is a high level of vacuum in the intake manifold e. In systems with "wet" type intake manifold e. SPi changes in manifold pressure can cause the fuel entering the vacuum hose to reach the MAP. To avoid this, a special trap is used and accordingly traced vacuum hose. If the fuel reaches the MAP sensor, its diaphragm may be damaged.

Therefore there is no risk of MAP sensor fuel penetration and contamination of the diaphragm, and therefore a special trap is not used.

When the MAP sensor is used as a separate component, inexpensive maintenance could be achieved. This can be seen in the attached diagram.

How it works. MAP Sensors. Engine Management. Related Resources. A diesel particulate filter DPF differential pressure sensor measures exhaust backpressure and signals when the power-train control module PCM should begin a regeneration Click here to learn more.

Typically found in fuel injected engines, the manifold absolute pressure MAP sensor is one of the sensors an engine control module ECM uses to calculate fuel injection for Whilst traditional braking components may not have changed much, the addition of electronic controls has made braking systems much safer and smarter than ever before