Fuel Injection Flashcards
On a carburetor engine, the fuel filter usually attaches to the line with:
a. Spring - lock fittings
b. Flare - nut fittings
c. Compression fittings
d. Hose clamps
d. Hose clamps
All of the following may be used for fuel lines EXCEPT:
a. Copper tubing
b. Neoprene hose
c. Nylon tubing
d. Steel tubing
a. Copper tubing
A good mechanical fuel pump operating at 500 rpm will delivery how much pressure?
a. 5 to 10 psi
b. 10 to 15 psi
c. 15 to 25 psi
d. 25 to 30 psi
a. 5 to 10 psi
Which of the following is the typical operating pressure range of a throttle body injection system?
a. 5 to 10 psi
b. 10 to 15 psi
c. 15 to 25 psi
d. 25 to 30 psi
b. 10 to 15 psi
On a fuel injection system, all of the following can cause low residual pressure EXCEPT:
a. Faulty fuel pump check valve
b. Leaking injector
c. Defective pressure regulator
d. A clogged fuel filter
d. A clogged fuel filter
With the fuel pump running and a pressure gauge installed, applying vacuum to the fuel pressure regulator should case the gauge reading to:
a. Increase about 5 to 7 psi
b. Increase about 10 to 15 psi
c. Decrease about 5 to 10 psi
d. Decrease about 10 to 15 psi
c. Decrease about 5 to 10 psi
The primary purpose of the pressure regulator in a fuel injection system is to:
a. Limit pressure produced by the pump
b. Maintain uniform pressure at the injection
c. Control the air fuel ratio
d. Maintain residual pressure for quick start up
b. Maintain uniform pressure at the injection?
The signal carried by the ground wire on a potentiometer is also known as:
a. Signal voltage
b. Reference voltage
c. Return voltage
d. System voltage
c. Return voltage
An oscilloscope can be used to monitor electronic injectors’:
a. Opening pressure and delivery volume
b. Solenoid coil resistance
c. Pulse width and duty cycle
c. Pulse width and duty cycle
To check the boost pressure gauge of a turbo charger, a pressure gauge is installed in the:
a. Compressor side of the turbo
b. Turbine side of the turbo
c. Waste gate of the turbo
d. Intake manifold
d. Intake manifold
The cause of a MIL not lighting during a bulb check when the ignition is switched on can be all of the following EXCEPT:
a. A faulty circuit
b. A DTC in memory
c. A burned out bulb
d. An internal PCM failure
b. A DTC in memory
A failure that set a soft code in the PCM memory is one that:
a. Exists at the time of testing
b. Indicates a top priority problem
c. Occurred in the past but longer exists
d. Can be located with a diagnostic chart
c. Occurred in the past but no longer exists
During open loop operation, the PCM controls fuel metering based on:
a. Engine speed, load, temperature, and its own program
b. Feed back information from the oxygen sensor
c. The stoichiometric air fuel ratio
d. Learned information in adaptive memory
a. Engine speed, load, temperature, and its own program
When measured with a DVOM, the voltage drop across the main PCM ground connection should be:
a. 1.0 volt or less
b. 0.1 volt or less
c. 0.001 volt or less
d. 0.0001 volt or less
b. 0.1 volt or less
Excessive voltage drop across a high resistance ground connection in series with a sensor will cause:
a. Sensor reference voltage to decrease
b. Sensor reference voltage to increase
c. Sensor signal voltage to decrease
d. Sensor signal voltage to increase
c. Sensor signal voltage to decrease
Regardless of sensor design, what attribute of a speed signal does the PCM process to determine speed?
a. Frequency
b. Amplitude
c. Voltage
d. Duty cycle
a. Frequency
With the engine operating in closed loop, the oxygen sensor signal display on a lab scope is evenly cycling between about 460 mv and 900 mv with even amplitude and rounded peaks. This indicates:
a. Normal operation
b. A lean fuel mixture
c. A rich fuel mixture
d. A poor ground connection
c. A rich fuel mixture
What type of sensor is a variable resistor that provides an analog voltage signal to the PCM based on motion or position?
a. Thermistor
b. Potentiometer
c. Piezoresistive
d. Hall effect switch
b. Potentiometer
The analog voltage signal of an NTC thermistor will:
a. Decrease as temperature increases
b. Increase as temperature increases
c. Be about the 5 volts on most application
d. Be high if the sensor is shorted to ground
a. Decrease as the temperature increases
If the total cycling time of a PWM signal is 5 ms and the solenoid is energized for 2 ms during each cycle, the duty cycle of the solenoid would be:
a. 20%
b. 40%
c. 60%
d. 80%
b. 40%
Fuel injection systems can lower emissions:
a. By matching the air fuel ratio to engine requirements
b. Only at high speed
c. By using the intake manifold to vaporize fuel
d. By matching engine speed to load conditions
a. By matching the air fuel ratio to engine requirements
Tech A says an inoperative exhaust gas recirculation system can increase NOx.
Tech B says an inoperative EGR system can result in pinging and detonation.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Tech A says the output from one computer can act as an input for another computer.
Tech B says late model computers have self diagnostic capabilities and can store trouble codes.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
An OBD 1 system typically includes:
a. Short term fuel trim capability
b. Adaptive learning capability
c. Self diagnostic capability
d. All of the above
d. All of the above
Which of the following is NOT true of a fuel injected engine?
a. The computer controls the air fuel ratio by switching injectors on and off
b. The pulse width is increased to supply more fuel to the engine
c. To lean out the mixture, the computer opens the air bleeds
d. Engine speed determines the injector switching rate
c. To lean out the mixture, the computer opens the air bleeds
Tech A says a throttle position sensor may be either a rotary or a linear potentiometer.
Tech B says a TPS may be a simple on/off switch.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B?
An OBD 2 self test program performs which of these tests?
a. Test each sensor for proper operation
b. Test each input circuit for proper operation
c. Compare incoming data with data in memory
d. All of the above
d. All of the above
Long term fuel trim refers to:
a. Self diagnostic capability
b. Adaptive learning capability
c. Engine mapping
d. None of the above
b. Adaptive learning capability
Tech A says OBD 2 equipped vehicles have a standardized DLC.
Tech B says OBD 2 equipped vehicles may have as many as four heated oxygen sensors.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
Both A and B
An OBD 2 self test program performs which of these tests?
a. Check the fuel evaporative system for integrity
b. Monitor the catalytic converter oxygen storage capability
c. Monitor engine operation for misfires
d. All of the above
d. All of the above
Tech A says MAF sensors may use either a hot wire or heated film circuit.
Tech B says automatic transmission operations is controlled by the PCM or transmission control modules in many late model vehicles.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Tech A says an exhaust ga oxygen sensor with two wires relies on the exhaust manifold for its ground circuit.
Tech B says the computer ignores oxygen sensors in closed loop operation.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
d. Neither A nor B
Tech A says “peak and hold” refers to a method of controlling current to the fuel injector.
Tech B says the wave form of a “peak and hold” circuit normally contains two spikes.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Fuel injectors in pulsed fuel injection systems:
a. Have an on time measured in ms
b. Match frequency to engine speed
c. can be diagnosed with lab type oscilloscopes
d. All of the above
d. All of the above
The fuel pump relay in port fuel injection systems may be controlled by all of the following EXCEPT:
a. A micro switch in the vane air flow meter
b. The engine coolant temperature sensor
c. the tachometer signal
d. The starting circuit
b. The engine coolant temperature sensor
The cold start injector on Bosch L Jetronic and K Jetronic systems is controlled by:
a. The ignition circuit
b. The thermo time switch
c. The auxiliary air valve
d. The PCM
b. The thermo time switch
Tech A says Bosch K Jetronic fuel injection systems operate at higher fuel pressures than other commonly used systems.
Tech B says fuel metering in the K Jetronic system relies on a balance of force between incoming air and control pressure exerted on the control plunger.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
A hot wire or heated film MAF sensor measures:
a. Air flow velocity entering the engine
b. Barometric absolute pressure
c. Air temperature in a turbocharged system
d. Molecular mass of air entering the engine
d. Molecular mass of air entering the engine
All of the following are likely filter locations in a fuel injection system EXCEPT:
a. In the pressure regulator
b. At the fuel pump
c. In the fuel line
d. In the fuel injectors
a. In the pressure regulator
A cold start injector is a:
a. Mechanical continuous injector
b. Solenoid operated auxiliary injector
c. Mechanical intermittent injector
d. Dual fire electronic actuator
b. Solenoid operated auxiliary injector
NOx forms in an engine under:
a. High pressure and low temperature
b. Low pressure and low temperature
c. High temperature and high pressure
d. All of the above
c. High temperature and high pressure
Photo chemical smog is a result of:
a. Sunlight + NOx + HC
b. Sunlight + NOx + CO
c. Sunlight + CO + HC
d. Sunlight + NOx + CO2
a. Sunlight + NOx + HC
Tech A says the throttle in a multipoint gasoline fuel injection system is located between the injectors and the manifold.
Tech B says the throttle in an EFI system operates the same as a throttle on a carbureted engine.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
b. B only
Tech A says throttle body injection systems are electronic injection systems.
Tech B says TBI systems require fuel pressure regulators.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Bosch L Jetronic and similar systems measure air flow with a:
a. Manifold absolute pressure sensor
b. Hot wire air flow sensor
c. Vane type air flow sensor
d. Air charge temperature sensor
c. Vane type air flow sensor
Tech A says Bosch K Jetronic systems are mechanical injection systems that use an air sensor plate and fuel distributor.
Tech B says Bosch K systems are continuous injection systems.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Tech A says the voltage spike from an injector can be as high as 70 volts.
Tech B says the voltage spike helps to pull the injector closed quickly.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Tech A says the air bleed in a positive back pressure EGR valve is normally open.
Tech B says a positive back pressure EGR valve has no vacuum connection.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
a. Tech A only
In discussing an electronically controlled EGR system;
Tech A says a sensor informs the computer of how the system is functioning by a position signal.
Tech B says a sensor informs the computer by a pressure signal.
Who is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
c. Both A and B
Which of the following will increase NOx formation?
a. Enrich the air fuel mixture
b. Lower the compression ratio
c. Advance spark timing
d. Retard the spark timing
c. Advance spark timing
