General Explanation
The Variable Intake Air System (VIAS) is a feature in some Nissan and Infiniti vehicles that helps improve the car's performance and efficiency. It does this by changing the way air enters the engine based on how fast the car is going.
When the car is running at low or medium speeds, the VIAS closes a valve that makes the air travel a longer distance before it reaches the engine. This allows more air to be drawn into the engine, which helps it generate more power.
When the car is running at high speeds, the car's computer (Engine Control Module or ECM) sends a signal to open the valve. This makes the air travel a shorter distance, which reduces the resistance the air faces when it's being sucked into the engine. This helps the engine run more efficiently at high speeds.
Technical Explanation
Common Symptoms
Common symptoms of a faulty VIAS include loss of power when accelerating, decreased fuel efficiency, and a rough idle. The check engine light may also come on, and the car may fail emissions testing.
Diagnosing
Diagnosing a faulty VIAS typically involves scanning the vehicle's computer for error codes. This can be done using a diagnostic scanner tool. The mechanic will also visually inspect the VIAS and its components for any signs of damage or wear.
Common Repairs
Common repairs for a faulty VIAS include replacing the VIAS control solenoid valve or the VIAS power valve. In some cases, the entire VIAS assembly may need to be replaced. It's also possible that the ECM may need to be reprogrammed or replaced if it's not sending the correct signals to the VIAS.
In addition to these repairs, the mechanic will also clear any error codes from the vehicle's computer and perform a road test to ensure that the repairs have resolved the issue.
