Engine Performance, Emissions Flashcards
What are the three main pollutants in vehicle emissions?
Hydrocarbons (HC), Carbon Monoxide (CO), Nitrogen Oxides (NOx).
What causes high NOx emissions?
High combustion chamber temperatures (above 2500°F).
What system reduces NOx emissions?
The Exhaust Gas Recirculation (EGR) system.
What is one criterion most EVAP systems must meet before allowing a purge cycle?
The engine must be at normal operating temperature.
What is a common failure of a Throttle Position Sensor (TPS)?
Dropout on signal voltage.
What happens to the signal voltage of an Engine Coolant Temperature (ECT) sensor with a poor ground?
The signal voltage becomes erratic or incorrect.
What type of signal is produced when a solenoid circuit (such as a fuel injector) opens?
An inductive spike (high-voltage pulse).
What is the difference between the output of a magnetic pulse generator and a Hall-effect sensor?
A magnetic pulse generator produces an AC signal, while a Hall-effect sensor produces a DC digital signal.
What is the most effective device for testing computer inputs?
A digital multimeter (DMM) or a lab oscilloscope.
What controls turbo output by regulating the amount of exhaust gas entering the turbine housing?
The wastegate.
What can be used to check for leaks on the pressure side of a turbocharger system?
A smoke machine or boost pressure tester.
Which of these does NOT require engine horsepower to produce boost?
Turbocharger (it uses exhaust gases).
How many catalytic converters does a late-model vehicle typically have?
One to four, depending on the vehicle.
Which component is not part of the exhaust system?
Supercharger.
What is the main function of an oxygen sensor (O2 sensor)?
To monitor the air-fuel ratio and adjust fuel delivery.
What are three operating modes of OBD-II systems?
Continuous monitoring, stored fault detection, and pending fault detection.
What tool is used to retrieve stored fault codes from an OBD-II system?
A scan tool or OBD-II code reader.
What four methods can be used to check individual components in a vehicle system?
Voltage testing, resistance testing, current testing, and oscilloscope analysis.
What should a technician look for when checking a MAP sensor with a vacuum pump?
A change in signal voltage as vacuum is applied.
What type of battery is most commonly used in hybrid vehicles?
Lithium-ion (Li-ion) or Nickel-Metal Hydride (NiMH).
What system allows regenerative braking to recharge the battery in hybrid vehicles?
The regenerative braking system.
What is one major advantage of using tuned exhaust headers?
They increase engine breathing and improve performance.
What type of fuel can reduce HC and CO emissions but increase NOx emissions?
Ethanol-based fuels (like E85).
