• The gas pedal in your car is connected to the throttle valve -- this is the valve that regulates how much air enters the engine. So the gas pedal is really the air pedal.
   

• When you step on the gas pedal, the throttle valve opens up more, letting in more air. The engine control unit (ECU, the computer that controls all of the electronic components on your engine) "sees" the throttle valve open and increases the fuel rate in anticipation of more air entering the engine.
   

• It is important to increase the fuel rate as soon as the throttle valve opens; otherwise, when the gas pedal is first pressed, there may be a hesitation as some air reaches the cylinders without enough fuel in it.
   

• Sensors monitor the mass of air entering the engine, as well as the amount of oxygen in the exhaust. The ECU uses this information to fine-tune the fuel delivery so that the air-to-fuel ratio is just right.

• A fuel injector is nothing but an electronically controlled valve. It is supplied with pressurized fuel by the fuel pump in your car, and it is capable of opening and closing many times per second.

Inside a fuel injector.

• When the injector is energized, an electromagnet moves a plunger that opens the valve, allowing the pressurized fuel to squirt out through a tiny nozzle. The nozzle is designed to atomize the fuel -- to make as fine a mist as possible so that it can burn easily.
   

• The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open. This is called the pulse width, and it is controlled by the ECU.
   

• The injectors are mounted in the intake manifold so that they spray fuel directly at the intake valves. A pipe called the fuel rail supplies pressurized fuel to all of the injectors.
   

• In order to provide the right amount of fuel, the engine control unit is equipped with a whole lot of sensors. Let's take a look at some of them.

• In order to provide the correct amount of fuel for every operating condition, the engine control unit (ECU) has to monitor a huge number of input sensors. Here are just a few.
   

• Mass Airflow Sensor - Tells the ECU the mass of air entering the engine.

   

• Oxygen Sensor - Monitors the amount of oxygen in the exhaust so the ECU can determine how rich or lean the fuel mixture is and make adjustments accordingly.

   

• Throttle Position Sensor - Monitors the throttle valve position (Which determines how much air goes into the engine) so the ECU can respond quickly to changes, increasing or decreasing the fuel rate as necessary.

   

• Coolant Temperature Sensor - Allows the ECU to determine when the engine has reached its proper operating temperature.

   

• Voltage Sensor - Monitors the system voltage in the car so the ECU can raise the idle speed if voltage is dropping (Which would indicate a high electrical load).

   

• Manifold Absolute Pressure Sensor - Monitors the pressure of the air in the intake manifold. The amount of air being drawn into the engine is a good indication of how much power it is producing; and the more air that goes into the engine, the lower the manifold pressure, so this reading is used to gauge how much power is being produced.

   

• Engine Speed Sensor - Monitors engine speed, which is one of the factors used to calculate the pulse width.
   

• There are two main types of control for multi-port systems. The fuel injectors can all open at the same time, or each one can open just before the intake valve for its cylinder opens (This is called sequential multi-port fuel injection).
   

• The advantage of sequential fuel injection is that if the driver makes a sudden change, the system can respond more quickly because from the time the change is made, it only has to wait only until the next intake valve opens, instead of for the next complete revolution of the engine.

We install quality rebuilt and/or used engines. We also perform minor repairs that don't require engine removal.

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