This blog discusses what the atmospheric/barometric pressure sensor does and why we recommend keeping it active in your car.
Atmospheric and barometric (we'll use atmospheric from here on out) are synonyms for the sensor that measures the ambient air pressure around your car. This sensor allows the Engine Control Unit (ECU) to detect the altitude and temperature of your location based on air density. This information is important because the engine's performance relies on the amount of air entering it. The ECU performs calculations based on the volume of air coming into the engine to regulate its performance effectively.
We want the ECU to know the air density because at sea level the air is denser than somewhere in the mountains where the air is less dense. Or if you are in the freezing snow or a blistering desert, the temperature around your car also changes the air density. Without the ECU adjusting for these pressure changes, the engine can run poorly.Ā
Why would someone take out the atmospheric/barometric pressure sensor?
Some people decide to remove the secondary air injection system which has a component that contains the atmospheric pressure sensor. If this component is removed then the air density information to the ECU is lost as well. Secondary air pumps are known for their frequent failures. Although you can set an average air density for the ECU, it's not advisable.
Please also note that removing the secondary air injection system will cause a check engine light because emissions components are removed.Ā
iWire's Recommendation:
Keep the secondary air injection system intact, or add it back in if you purchase a car that has it deleted. To add it back, you would purchase the stock part that matches your year and model car and install it onto the engine.
StandaloneĀ ECU's
Some standalone ECUs feature an additional vacuum port for atmospheric or manifold pressure. We strongly recommend using this for atmospheric pressure rather than manifold pressure and employing a dedicated sensor for manifold pressure.
If you aren't sure if your standalone ECU has an atmospheric pressure sensor, we highly recommend confirming it and adding one if it does not. A standard MAP sensor can beĀ repurposed as an atmospheric pressure sensor if calibrated properly.Ā
Below are our connectors we carry in case you need to replace the Secondary Air Injection System:
Manifold Absolute Pressure (MAP) Sensor Plug A
Manifold Absolute Pressure (MAP) Sensor Plug B
Manifold Absolute Pressure (MAP) Sensor Plug C
