Your engine's air intake system, which is designed to optimize the air flow and cleanliness for use in the vehicle's engine. To run, your car's engine requires both fuel and air mixed at proper ratios for the torque and speed being asked of it. If the air is dirty or not moving into the engine fast enough, your car's efficiency and performance will suffer.
What Can Go Wrong With the Intake System?
The most common issue with intake systems is blockage or bad flow. This is usually caused by dirty filters that should be replaced. Leaks in the system, usually at seals at attachment points, can also cause the air flow to be sub-optimal.
Cold air intake is another issue that some engines will have. In very cold environments, the air coming in may have frozen water droplets in it which can prevent the evaporation of fuel droplets, causing them to not properly ignite in the combustion chamber. Modern engines usually pass the air over the engine to heat it before sending it into the intake. Filters can also help play a role, trapping some water molecules and even helping to heat the air through friction.
Intake Repair Options and DIY Maintenance
For the home mechanic or even just the car owner wanting to save a few dollars on intake repair, the replacement of air filters in most modern engines is low cost and often requires no tools at all. Many filter housings are easy to find (usually located on top and/or to one side of the engine) and have clips that can be opened to access the filter without tools. An easy inspection of the filter's cleanliness requires little knowledge; replacement is often under ten dollars.
Most oil change and auto repair shops check the air filter as part of routine checks during service. Replacing through them, however, can cost twice the shelf price of the filter itself, so a few dollars can be saved doing it yourself.