Question 1

You should not immerse the fuel rail, injectors, or pressure regulator in any type of cleaning  solvent.

Accepted Answer

A) True 
 B)False  True

Question 2

Always pressurize the fuel system before disconnecting any fuel system components.

Accepted Answer

A) True 
 B)False  False

Question 3

If the injectors and their electrical harness are visible but cannot be accessed without removing the upper intake manifold, injector operation can be checked by using a(n)____________________.

Accepted Answer

mechanic's stethoscope

Question 4

Most heated oxygen sensors have _____ wire(s)connected to them.

Accepted Answer

A) one 
B) two 
C) three 
D) four 
A) one 
B) two 
C) three 
D) four

Question 5

If the IAC pintle is extended too far, the motor can be damaged during installation.

Accepted Answer

A) True 
 B)False

Question 6

Injector cleaning is being discussed. Technician A uses a wire brush to clean the tips of the injectors. Technician B soaks the injector in cleaning solvent. Who is correct?

Accepted Answer

A) A only 
B) B only 
C) both A and B 
D) neither A nor B 
A) A only 
B) B only 
C) both A and B 
D) neither A nor B

Question 7

STFT adjustments are temporary and are not stored in the PCM's memory.

Accepted Answer

A) True 
 B)False

Question 8

While testing, a good pressure regulator diaphragm will hold ____________________.

Accepted Answer

The answer of While testing, a good pressure regulator diaphragm...

Question 9

It is impossible to visually check the spray pattern and volume of port system injectors.

Accepted Answer

A) True 
 B)False

Question 10

What is the difference between the pulse width of an injector and the duty cycle?

Accepted Answer

Pulse width is the time in mil

Question 11

Why will a leak in the ductwork between the MAF and the throttle body have an effect on the driveability of the vehicle?

Accepted Answer

Air leaking into the system after the MA

Question 12

Vacuum leaks in speed density systems can be verified by watching the _____ on a scan  tool.

Accepted Answer

A) O2 sensor cycle 
B) IAC counts 
C) mass airflow (MAF)voltage 
D) delta EGR (exhaust gas recirculation) 
A) O2 sensor cycle 
B) IAC counts 
C) mass airflow (MAF)voltage 
D) delta EGR (exhaust gas recirculation)

Question 13

All late-model engines use at least one ____________________ oxygen sensor.

Accepted Answer

The answer of All late-model engines use at least one...

Question 14

Which of the following would not cause the fuel pressure to drop to zero immediately after engine shut down?

Accepted Answer

A) leaking pressure regulator vacuum line 
B) leaking fuel pressure regulator 
C) leaking fuel pump check valve 
D) leaking fuel injector 
A) leaking pressure regulator vacuum line 
B) leaking fuel pressure regulator 
C) leaking fuel pump check valve 
D) leaking fuel injector

Question 15

A rich air/fuel mixture is being discussed. Technician A says oxygen content in the exhaust will be high. Technician B says the O2 sensor voltage will be high. Who is correct?

Accepted Answer

A) A only 
B) B only 
C) both A and B 
D) neither A nor B 
A) A only 
B) B only 
C) both A and B 
D) neither A nor B

Question 16

When cleaning the injectors with a pressurized injector cleaner, prior to starting the engine, ______.

Accepted Answer

A) remove the fuel pump relay or fuel pump fuse 
B) pinch off the fuel return hose 
C) connect the can of cleaner to the Schrader valve on the fuel rail 
D) All the answers are correct. 
A) remove the fuel pump relay or fuel pump fuse 
B) pinch off the fuel return hose 
C) connect the can of cleaner to the Schrader valve on the fuel rail 
D) All the answers are correct.

Question 17

The IAC motor cannot be actuated with a scan tool.

Accepted Answer

A) True 
 B)False

Question 18

Preliminary checks are being discussed. Technician A says to run specific fuel injection tests first. Technician B says most driveability concerns are caused by PCM-related problems. Who is correct?

Accepted Answer

A) A only 
B) B only 
C) both A and B 
D) neither A nor B 
A) A only 
B) B only 
C) both A and B 
D) neither A nor B

Question 19

A technician is testing a fuel injection system with a scan tool. While the engine is running in closed loop, he loosens a vacuum hose to create a small vacuum leak. Initially the STFT rises and the LTFT remains unchanged. After a few minutes the STFT returns to near zero and the LTFT rises. This test proves that ______.

Accepted Answer

A) the system is running rich 
B) the system is running lean 
C) the O2S sensor is faulty 
D) the system is working normally 
A) the system is running rich 
B) the system is running lean 
C) the O2S sensor is faulty 
D) the system is working normally

Question 20

When viewing injector patterns on a lab scope, the injector pulse end with a ______.

Accepted Answer

A) downward right angle 
B) first upward spike 
C) highest upward spike 
D) last upward spike 
A) downward right angle 
B) first upward spike 
C) highest upward spike 
D) last upward spike

Exam 31: Fuel Injection Diagnosis and Service

You should not immerse the fuel rail, injectors, or pressure regulator in any type of cleaning solvent.

Always pressurize the fuel system before disconnecting any fuel system components.

If the injectors and their electrical harness are visible but cannot be accessed without removing the upper intake manifold, injector operation can be checked by using a(n)____________________.

Most heated oxygen sensors have _____ wire(s)connected to them.

If the IAC pintle is extended too far, the motor can be damaged during installation.

Injector cleaning is being discussed. Technician A uses a wire brush to clean the tips of the injectors. Technician B soaks the injector in cleaning solvent. Who is correct?

STFT adjustments are temporary and are not stored in the PCM's memory.

While testing, a good pressure regulator diaphragm will hold ____________________.

It is impossible to visually check the spray pattern and volume of port system injectors.

What is the difference between the pulse width of an injector and the duty cycle?

Why will a leak in the ductwork between the MAF and the throttle body have an effect on the driveability of the vehicle?

Vacuum leaks in speed density systems can be verified by watching the _____ on a scan tool.

All late-model engines use at least one ____________________ oxygen sensor.

Which of the following would not cause the fuel pressure to drop to zero immediately after engine shut down?

A rich air/fuel mixture is being discussed. Technician A says oxygen content in the exhaust will be high. Technician B says the O2 sensor voltage will be high. Who is correct?

When cleaning the injectors with a pressurized injector cleaner, prior to starting the engine, ______.

The IAC motor cannot be actuated with a scan tool.

Preliminary checks are being discussed. Technician A says to run specific fuel injection tests first. Technician B says most driveability concerns are caused by PCM-related problems. Who is correct?

When viewing injector patterns on a lab scope, the injector pulse end with a ______.

Careers in the Automotive Industry

Workplace Skills

Basic Theories and Math

Automotive Systems

Hand Tools and Shop Equipment

Diagnostic Equipment and Special Tools

Working Safely in the Shop

Preventative Maintenance and Basic Services

Automotive Engine Designs and Diagnosis

Engine Disassembly and Cleaning

Lower-End Theory and Service

Upper-End Theory and Service

Engine Sealing and Reassembly

Lubricating and Cooling Systems

Basics of Electrical Systems

General Electrical System Diagnostics and Service

Batteries: Theory, Diagnosis, and Service

Starting and Motor Systems

Charging Systems

Lighting Systems

Instrumentation and Information Displays

Basics of Electronics and Computer Systems

Electrical Accessories

Engine Performance Systems

Detailed Diagnosis and Sensors

Ignition Systems

Ignition System Diagnosis and Service

Gasoline, Diesel and Other Fuels

Fuel Delivery Systems

Electronic Fuel Injection

Intake and Exhaust Systems

Emission Control Systems

Emission Control Diagnosis and Service

Hybrid Vehicles

Electric Vehicles

Clutches

Manual Transmissions and Transaxles

Manual Transmission and Transaxle Service

Drive Axles and Differentials

Automatic Transmissions and Transaxles

Electronic Automatic Transmissions

Automatic Transmission and Transaxle Service

Four- and All-Wheel Drive

Tires and Wheels

Suspension Systems

Steering Systems

Restraint Systems: Theory, Diagnosis, and Service

Wheel Alignment

Brake Systems

Drum Brakes

Disc Brakes

Antilock Brake, Traction Control, and Stability Control Systems

Heating and Air Conditioning

Heating and Air Conditioning Diagnosis and Service

Filters

A rich air/fuel mixture is being discussed. Technician A says oxygen content in the exhaust will be high. Technician B says the O₂ sensor voltage will be high. Who is correct?