The electrical resistance of the wire increases as the wires temperature increases, which limits electrical current flowing through the circuit. When air flows past the wire, it cools, decreasing its resistance, which in turn allows more current to flow through the circuit. However, as more current flows, the wires temperature increases until the resistance reaches equilibrium again. Throttle Body. The throttlebody is the part of the air intake system that controls the amount of air flowing into an engines combustion chamber. It consists of a bored housing that contains a throttle plate that rotates on a shaft. When the accelerator is depressed, the throttle plate opens and allows air into the engine. When the accelerator is released, the throttle plate closes and effectively chokes off air flow into the combustion chamber. This process effectively controls the rate of combustion and ultimately the speed of the vehicle. The throttle body is usually located between the air filter box and the intake manifold, and it is usually located near the mass airflow sensor. Cold air intake and how it works. A cold air intake is used to bring cooler air into a cars engine, to increase engine power and efficiency. The most efficient intake systems utilise an air box which is sized to complement the engine and will extend the power band of the engine. The intake snorkel, or the opening for the intake air to enter the system, must be large enough to ensure sufficient air is available to the engine under all conditions from idle to full throttle. Cold air intakes operate on the principle of increasing the amount of oxygen available for combustion with fuel. Because cooler air has a higher density greater mass per unit volume, cold air intakes generally work by introducing cooler air from outside the hot engine bay. The most basic cold air intake replaces the stock air box with a short metal or plastic tube leading to a conical air filter, called a short ram air intake. The power gained by this method can vary depending on how restrictive the factory air box is. Well designed intakes use heat shields to isolate the air filter from the rest of the engine compartment, providing cooler air from the front or side of the engine bay. Some systems called fender mount move the filter into the fender wall, this system draws air up through the fender wall which provides even more isolation and still cooler air. How it improves your air intake system. Some of the advantages of having a cold air intake include an increase in horsepower and torque. As a cold air intake draws in a higher volume of air which may be much cooler, your engine can breathe easier than with a limiting stock system. With your combustion chamber filled by cooler, oxygen rich air, fuel burns at a more efficient mixture. You get more power and torque out of every drop of fuel when its combined with the right amount of air. Another advantage to having a cold air intake is improved throttle response and fuel economy in most cases. Stock intakes often deliver warmer, fuel rich combustion mixtures that cause your engine to lose power and responsiveness while running hotter and more sluggishly. Cold air intakes can help your fuel economy by improving your air to fuel ratio.