Electronic Fuel Injection Flashcards
(22 cards)
What are the three types of fuel injectors?
- throttle body injection
- multiport injection
- direct injection
What is throttle body injection?
- fuel injector is on the throttle body
- older design (1998 and older)
What is multiport injection?
- uses 1 injector for each cylinder
- fuel is injected outside the combustion chamber (before the intake valve).
- fuel cleans the intake valves as it travels to combustion chamber.
What is direct injection?
- fuel is injected inside the combustion chamber.
- intake valves cake up with carbon
What is the function of the power train control module (PCM) (Also known as Engine control module).
- Essentially, it is the “brain” of the vehicles powertrain; it processes fuel quantity, spark timing, idle, and emission control.
What type of info do the sensors provide to the PCM?
- engine speed
- throttle position
- accelerator pedal position
- coolant temperature
- air temperature
- engine load
- knock (detonation).
The PCM uses camshaft position info to determine when to: (hint: there are three things related to spark, timing, and fuel)
- fire the spark plugs
- trigger fuel injectors
- alter/change valve timing
When you are at a red light, what is the manifold pressure and throttle position?
- throttle is closed
- manifold pressure is low
What is the manifold pressure and throttle position when you are going up a steep hill?
- pressure is high
- throttle is wide open
What voltage does the throttle position read when it is at idle vs wide open?
idle: .5 volts
WOT: 4.5 volts
What does the PCM do when the coolant temperatures are cold and hot?
Increase fuel when engine is cold, and decrease it when it is warm.
What does the manifold absolute pressure (MAP) sensor sense
- it senses intake manifold pressure and sends it to the PCM to correct the AFM.
What does the mass air flow (MAF) sensor sense?
MAF senses/measures how much air the engine is drawing in.
What does a detonation/knock sensor sense?
- it detects detonation so the PCM can respond by adjusting the spark to combat unwanted detonation.
Why is it important for the PCM to receive info on how much fuel is injected to the cylinder?
- Improve the fuel economy
- Lower emission levels
Where can you find the oxygen and air fuel ratio sensors, and what do they sense?
- they are located on the exhaust system
- They send info regarding the AFM to the pcm, so it can know how much fuel was burnt/used.
What does the 02 sensor tell the pcm?
- it tells the PCM if the AFM is too rich or lean.
What is the ideal AFM ratio (stochiometric)?
14.7(air):1(fuel)
How does the 02 sensor work?
- reads the oxygen left over in the exhaust gases and compares it with the oxygen in the atmosphere
What is the 02 sensor saying when it reads .6 - 1 volts?
The mixture is too rich!
What is the 02 sensor saying when it produces .1 - .4 volts?
The mixture is too lean!
Explain these air fuel mixtures:
Rich = ____ fuel and ____ air
Lean = ____ fuel and ____air
More or less?
- rich = more fuel, less air air
- lean = less fuel, more air
