1. Air-Fuel Mixture Ratio: A vacuum leak disrupts the engine's air-fuel mixture. When there's a leak in the vacuum system, unmetered air enters the engine, causing the air-fuel ratio to become leaner (more air and less fuel).
2. Idle Speed: A vacuum leak can cause the engine to idle roughly or even stall. To compensate for the lean mixture, the engine's computer (ECU) might increase the amount of fuel being injected to smooth out the idle. This richer mixture results in reduced fuel efficiency.
3. Engine Efficiency: Vacuum leaks reduce engine efficiency. When the air-fuel mixture isn't balanced correctly, the engine has to work harder to produce the same amount of power. This overworking decreases fuel efficiency.
4. Oxygen Sensor Malfunction: A vacuum leak can also affect the oxygen sensor's readings. The oxygen sensor is responsible for monitoring the air-fuel ratio and feeding back that information to the ECU. With a vacuum leak, the oxygen sensor receives inaccurate readings and adjusts the fuel injection accordingly, potentially leading to poor fuel economy.
It's important to note that the impact of a vacuum leak on gas mileage can vary depending on the severity of the leak and the specific vehicle. Small vacuum leaks might cause a slight decrease in fuel efficiency, while larger leaks can lead to significant loss of MPG.
If you suspect a vacuum leak in your truck, it's advisable to have it inspected and repaired by a qualified mechanic.
