Replacing the air filter with a K&N (or any other so called performance air filter) on vehicles with fuel-injected, computer-controlled gasoline engines—such as those manufactured from the early 1980s to the present—or diesel engines does not improve fuel economy. Go check with K & N and they will agree.
We certainly understand why it is theoretically possible for a consumer to experience a mileage increase after installing a K&N air filter or intake system, however, we do not go so far as to make a general claim that our air filters and intake systems will provide an increase in mileage.
Definition of theory
Idea formed by speculation: an idea of or belief about something arrived at through speculation or conjecture
What many people don't realize and what many others simply forget to consider is that there is a throttle valve
connected to your gas pedal that is constantly restricting the air flow into the engine. The only time it is not restricting the airflow is when it is at wide open (WOT). The throttle valve
determines how much air enters the engine, and the engine computer
(for fuel injected engines) determines how much fuel to mix with the air. Several factors influence how the computer determines this, but the result is basically the same: a fixed Air/Fuel Ratio will be supplied to the cylinders.
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