Question 1

The volumetric efficiency of an engine can be increased to more than 100% by use of ________.

Accepted Answer

A)  103 octane fuel 
B)  turbocharging 
C)  5-valve cylinder heads 
D)  a second overdrive gear 
A)  103 octane fuel 
B)  turbocharging 
C)  5-valve cylinder heads 
D)  a second overdrive gear B

Question 2

If Lambda is 0.98, this means the ________.

Accepted Answer

A)  mixture is lean 
B)  air-fuel mixture is slightly rich 
C)  air-fuel mixture is within 2% of stoichiometric 
D)  Both B and C 
A)  mixture is lean 
B)  air-fuel mixture is slightly rich 
C)  air-fuel mixture is within 2% of stoichiometric 
D)  Both B and C D

Question 3

The MAF sensor may give an inaccurate measurement if the ________ is modified.

Accepted Answer

A)  AC system 
B)  cooling fan 
C)  radiator 
D)  air inlet system 
A)  AC system 
B)  cooling fan 
C)  radiator 
D)  air inlet system D

Question 4

A contaminated or defective MAF sensor is indicated if ________.

Accepted Answer

A)  the fuel trim numbers are within ± 2% 
B)  the fuel trim number follows the airflow 
C)  the BARO reading is lower than normal 
D)  the VE is bad 
A)  the fuel trim numbers are within ± 2% 
B)  the fuel trim number follows the airflow 
C)  the BARO reading is lower than normal 
D)  the VE is bad

Question 5

The primary purpose of the fuel trim is to keep the air-fuel mixture as close to ________ as possible.

Accepted Answer

A)  One 
B)  Lambda 
C)  14.7:1 
D)  Both B and C 
A)  One 
B)  Lambda 
C)  14.7:1 
D)  Both B and C

Question 6

Older fuel injection systems (multiport or gang-fired systems) were capable of providing an air-fuel mixture within an accuracy of about ________% of stoichiometric.

Accepted Answer

A)  4 
B)  8 
C)  6 
D)  2 
A)  4 
B)  8 
C)  6 
D)  2

Question 7

If the air-fuel ratio is 14.7:1, what is Lambda?

Accepted Answer

A)  1.1 
B)  0.9 
C)  1.0 
D)  14.7 
A)  1.1 
B)  0.9 
C)  1.0 
D)  14.7

Question 8

Fuel trim provides a method that is capable of changing the amount of fuel delivered to the engine based on feedback from which of these input sensors?

Accepted Answer

A)  Engine coolant temperature 
B)  Oxygen sensor(s) 
C)  TPS (Throttle Position Sensor) 
D)  MAF (Mass Air Flow) 
A)  Engine coolant temperature 
B)  Oxygen sensor(s) 
C)  TPS (Throttle Position Sensor) 
D)  MAF (Mass Air Flow)

Question 9

The equivalence ratio (ER) is ________ lambda.

Accepted Answer

A)  5% higher than 
B)  the same as 
C)  the inverse of 
D)  5% lower than 
A)  5% higher than 
B)  the same as 
C)  the inverse of 
D)  5% lower than

Question 10

Technician A says that air-fuel ratio lambda numbers lower than 1.0 indicate a lean mixture. Technician B says that air-fuel ratio lambda numbers higher than 1.0 indicate a rich mixture. Which technician is correct?

Accepted Answer

A)  Technician A only 
B)  Technician B only 
C)  Both technicians A and B 
D)  Neither technician A nor B 
A)  Technician A only 
B)  Technician B only 
C)  Both technicians A and B 
D)  Neither technician A nor B

Question 11

The catalytic converter is most efficient when the air-fuel mixture is ________.

Accepted Answer

A)  at 14.7:1 air/fuel ration 
B)  at 1.0 lambda 
C)  varying from rich to lean (0.9 to 1.1 lambda) 
D)  Both A and B 
A)  at 14.7:1 air/fuel ration 
B)  at 1.0 lambda 
C)  varying from rich to lean (0.9 to 1.1 lambda) 
D)  Both A and B

Question 12

Technician A says that the primary purpose of fuel trim is to keep the air-fuel mixture as close to 14.7:1 as possible. Technician B says that when the air-fuel ratio is at 14.7:1, the efficiency of the catalytic converter is the lowest. Which technician is correct?

Accepted Answer

A)  Technician A only 
B)  Technician B only 
C)  Both technicians A and B 
D)  Neither technician A nor B 
A)  Technician A only 
B)  Technician B only 
C)  Both technicians A and B 
D)  Neither technician A nor B

Question 13

In a speed density system, what does NOT needed to calculate base pulse width?

Accepted Answer

A)  Amount of EGR 
B)  BARO sensor data 
C)  Air temperature 
D)  Oxygen in exhaust from the oxygen sensor 
A)  Amount of EGR 
B)  BARO sensor data 
C)  Air temperature 
D)  Oxygen in exhaust from the oxygen sensor

Question 14

Base pulse width is determined by ________.

Accepted Answer

A)  oxygen sensor data 
B)  computer calculations 
C)  input from many sensors, except the oxygen sensor 
D)  Both B and C 
A)  oxygen sensor data 
B)  computer calculations 
C)  input from many sensors, except the oxygen sensor 
D)  Both B and C

Question 15

What is NOT true about short-term fuel trim?

Accepted Answer

A)  Able to react quickly to add or subtract fuel 
B)  Can add or subtract a large amount of fuel 
C)  Is expressed in percentages 
D)  Uses the oxygen sensor 
A)  Able to react quickly to add or subtract fuel 
B)  Can add or subtract a large amount of fuel 
C)  Is expressed in percentages 
D)  Uses the oxygen sensor

Question 16

A Lambda of 0.97 means that the engine is operating ________ rich and has an air-fuel mixture of ________.

Accepted Answer

A)  13%; 15.7:1 
B)  1%; 14.7:1 
C)  0.3%; 14.1:1 
D)  3%; 14.3:1 
A)  13%; 15.7:1 
B)  1%; 14.7:1 
C)  0.3%; 14.1:1 
D)  3%; 14.3:1

Question 17

To determine the air-fuel ratio if Lambda is given, multiply Lambda times ________.

Accepted Answer

A)  14.7 
B)  1.47 
C)  2.47 
D)  0.47 
A)  14.7 
B)  1.47 
C)  2.47 
D)  0.47

Question 18

The air at high altitude has ________.

Accepted Answer

A)  Less than 21% oxygen 
B)  Higher pressure 
C)  Higher density 
D)  21% oxygen 
A)  Less than 21% oxygen 
B)  Higher pressure 
C)  Higher density 
D)  21% oxygen

Question 19

A Nissan vehicle is being checked using a scan tool and Alpha is 107. This means ________.

Accepted Answer

A)  the PCM represents STFT only 
B)  the PCM represents LTFT only 
C)  the PCM is subtracting fuel 
D)  the PCM is adding fuel 
A)  the PCM represents STFT only 
B)  the PCM represents LTFT only 
C)  the PCM is subtracting fuel 
D)  the PCM is adding fuel

Question 20

Injector pulse width is measured in ________.

Accepted Answer

A)  milliseconds (mS) 
B)  duty cycle (%) 
C)  frequency (Hz) 
D)  percentage (%) 
A)  milliseconds (mS) 
B)  duty cycle (%) 
C)  frequency (Hz) 
D)  percentage (%)

Exam 20: Fuel Trim Diagnosis

The volumetric efficiency of an engine can be increased to more than 100% by use of ________.

If Lambda is 0.98, this means the ________.

The MAF sensor may give an inaccurate measurement if the ________ is modified.

A contaminated or defective MAF sensor is indicated if ________.

The primary purpose of the fuel trim is to keep the air-fuel mixture as close to ________ as possible.

Older fuel injection systems (multiport or gang-fired systems) were capable of providing an air-fuel mixture within an accuracy of about ________% of stoichiometric.

If the air-fuel ratio is 14.7:1, what is Lambda?

Fuel trim provides a method that is capable of changing the amount of fuel delivered to the engine based on feedback from which of these input sensors?

The equivalence ratio (ER) is ________ lambda.

Technician A says that air-fuel ratio lambda numbers lower than 1.0 indicate a lean mixture. Technician B says that air-fuel ratio lambda numbers higher than 1.0 indicate a rich mixture. Which technician is correct?

The catalytic converter is most efficient when the air-fuel mixture is ________.

Technician A says that the primary purpose of fuel trim is to keep the air-fuel mixture as close to 14.7:1 as possible. Technician B says that when the air-fuel ratio is at 14.7:1, the efficiency of the catalytic converter is the lowest. Which technician is correct?

In a speed density system, what does NOT needed to calculate base pulse width?

Base pulse width is determined by ________.

What is NOT true about short-term fuel trim?

A Lambda of 0.97 means that the engine is operating ________ rich and has an air-fuel mixture of ________.

To determine the air-fuel ratio if Lambda is given, multiply Lambda times ________.

The air at high altitude has ________.

A Nissan vehicle is being checked using a scan tool and Alpha is 107. This means ________.

Injector pulse width is measured in ________.

The Diagnostic Process

Gasoline, Alternative Fuels, and Diesel Fuels

Circuit Testers and Digital Meters

Oscilloscopes and Dsos

Engine Systems

In-Vehicle Engine Service

Valve Train and Variable Valve Timing Diagnosis

Engine and Misfire Diagnosis

Can and Network Communications

Onboard Diagnosis

Global Obd Ii and Mode 06

Immobilizer Systems

Starting and Charging System Diagnosis

Ignition System Operation and Diagnosis

Temperature Sensors

Throttle Position Tp Sensors

Map and Maf Sensors

Electronic Throttle Control Systems

Oxygen Sensors

Fuel Pumps, Lines, and Filters

Fuel-Injection Components and Operation

Gasoline Direct-Injection Systems

Fuel-Injection System Diagnosis and Service

Electronic Transmission Controls

Vehicle Emissions Standards and Testing

Emission Control Devices Operation and Diagnosis

Module Reprogramming

Symptom-Based Diagnosis

Filters

A Lambda of 0.97 means that the engine is operating rich and has an air-fuel mixture of .