What is a throttle?  You have all heard of it, but what exactly does it do?  Any guesses?  The most common usage of the word relates to aircraft, as in increase throttle for lift-off, but it may surprise you to know that every vehicle that you drive has a throttle as well.

In a vehicle, the throttle is a valve that directly controls the amount of air that enters the engine, which in turn affects the air/fuel mixture that causes combustion in the internal combustion engine.  Usually this valve is a butterfly valve and it is located at the front of the intake manifold.  This is especially true for fuel-injected engines.  For carbureted engines the throttle is found on the carburetor.

For modern engines that have an ECU (engine control unit), the throttle is controlled by the ECU, choosing the precise air-intake necessary for optimum operation of the engine.

So how does it all work?  When the accelerator pedal is depressed, that motion is sent via the throttle cable and that activates the throttle linkage, which in turn moves the throttle plate (butterfly valve).   In vehicles with an ECU sensors do the job of the linkage, sending a signal which operates the valve.

The final step in this process involves the ECU determining the amount of air and making a corresponding decision that allows the right amount of fuel to mix with the air for proper combustion.  Interestingly, in older cars, the throttle was very easy to reach and if your engine was idling rough all you did was open the throttle a bit and tighten the screw that released it.  Problem solved!  It has gotten a bit more complicated over the years.

So much happening inside that engine when you drive, and it all works perfectly time and time again.  As the engine operates, signals are sent to the transmission, the brakes, the fuel pump and other parts so that your vehicle will run at optimum efficiency.  It really is amazing how far we have come regarding the internal combustion engine, but really, the operating principle is the same as it was when the first engine was put in the first car over 100 years ago.

The throttle is an easy fix if you are a do-it-yourselfer with car repairs.  It is quite easy to get to, is not expensive, and is a repair that most home mechanics will undertake on their own.  Go to any reliable salvage yard and spend much less on this particular replacement part.