Fuel Injection Flashcards
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Multi-point fuel injection systems have a fuel injector for each cylinder, usually positioned so that they spray directly at what?
The intake valve. ( As new engines were designed, throttle body fuel injection was replaced by multi-point injection. These systems have a fuel injector for each cylinder, usually positioned so that they spray directly at the intake valve. These systems provide more accurate fuel metering and quicker response.)
As the automobile evolved, the carburetor got more and more complicated, trying to handle all of the operating requirements. How many different circuits did a carburetor need to handle some of the tasks?
Five. (As the automobile evolved, the carburetor got more and more complicated trying to handle all of the operating requirements. For instance, to handle some of these tasks, carburetors had five different circuits: the main circuit, idle circuit, accelerator pump, power enrichment circuit and the choke.)
Initially, carburetors were replaced with ______ systems that incorporated electrically controlled fuel-injector valves into the ______.
Throttle body fuel injection systems; throttle body. (At first, carburetors were replaced with throttle body fuel injection systems (also known as single point or central fuel injection systems) that incorporated electrically controlled fuel-injector valves into the throttle body. These were almost a bolt-in replacement for the carburetor, so the automakers didn’t have to make any drastic changes to their engine designs.)
The amount of time the fuel injector stays open is called what?
Pulse width. (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.)
When the fuel injectors are mounted in the intake manifold, the pressurized fuel is supplied to the injectors by a pipe called the ______.
Fuel rail. (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.)
What is the name of the sensor that monitors the pressure of the air in the intake manifold?
The manifold absolute pressure sensor. (The 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.)
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. What is this called?
Sequential multi-port fuel injection. (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 until the next intake valve opens, not for the next complete revolution of the engine.)
What is the purpose of the Mass airflow sensor?
Tells the ECU the mass of air entering the engine.
What is the purpose of the Oxygen sensor(s)?
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.
What is the purpose of the 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.
What is the purpose of the Coolant temperature sensor?
Allows the ECU to determine when the engine has reached its proper operating temperature.
What is the purpose of the 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).
What is the purpose of the Manifold absolute pressure sensor?
Monitors the pressure of the air in the intake manifold.
What is the purpose of the Engine speed sensor?
Monitors engine speed, which is one of the factors used to calculate the pulse width.
