Fuels and Ignition Systems Automotive Repair …...Automotive Repair Technician 5 : Engine Fuels and Ignition Systems Lesson 1 Overview In this lesson, you'll cover gasoline, alternative

Automotive Repair Technician 5 : EngineFuels and Ignition Systems

Lesson 1 Overview

In this lesson, you'll cover

gasoline, alternative fuels,

and diesel fuels along with

the fundamentals,

diagnosis, and service of

engine ignition systems.

1.1 Identify gasoline,alternative fuels, anddiesel fuelsEngine Fuels

READING ASSIGNMENT

Read this assignment. Then read Chapter 66, 67, and 68 in your textbook.

Gasoline

Chapter 66 explains the chemical composition of gasoline, describes

the process of refining gasoline, and discusses how volatility affects

drivability. You’ll learn about gasoline combustion and how best to

Page 1Copyright Penn Foster, Inc. 2019 Course Version: 1

avoid abnormal combustion. In addition, this chapter covers the

benefits of using gasoline additives, reformulating gasoline, and

blending gasoline. Safety precautions for working with gasoline are

also discussed.

The following video and animation links from the author’s website may

help you better understand the textbook and your assignments.

Gasoline (www.jameshalderman.com/links/book_at/vid/ch66/vide

o_frame.html)

In-Line Fuel Blending (jameshalderman.com/links/a8/html5/Fuel_

Blending_In-Line-Chapter_66-A8.html)

Sequential Fuel Blending (jameshalderman.com/links/a8/html5/F

uel_Blending_Sequential-Chapter_66-A8.html)

Splash Fuel Blending (jameshalderman.com/links/a8/html5/Fuel_

Blending_Splash-Chapter_66-A8.html)

Fuel Mileage and Range, Gasoline (jameshalderman.com/links/a

8/html5/fuel_mileage_gas.html)

Fuel Mileage and Range, Hybrid (jameshalderman.com/links/a8/h

tml5/fuel_mileage_hybrid.html)

When a rich mixture is detected and the fuel gauge reads full, you

should check the charcoal canister outlet to the engine for blockage.

This will verify whether liquid gas is being sucked into the engine. You

can do this by blocking the line temporarily and taking several oxygen

sensor readings with a voltmeter or scan tool.

Search the Internet to find out how the octane of gasoline is


http://www.jameshalderman.com/links/book_at/vid/ch66/video_frame.html

http://jameshalderman.com/links/a8/html5/Fuel_Blending_In-Line-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/Fuel_Blending_Sequential-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/Fuel_Blending_Splash-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_gas.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_hybrid.html

determined.

Measuring Alcohol Content in Gasoline

This exercise will help you understand the chemical composition of

gasoline and the process of refining gasoline. Before beginning,

review page 762 in your textbook.

Materials and Equipment

1 pair of safety glasses

1 red gasoline can (one- to two-gallon capacity)

1 500-mL Erlenmeyer flask with neoprene stopper

Steps

1. Go to a local gas station and purchase about ½ gallon of regular

gasoline

2. Fill the Erlenmeyer flask with gas to the 200-mL line

3. Add 20 mL of water (10%) to the flask

4. Place the stopper in the top and shake the flask vigorously.

Remove the stopper several times during this process to release

any pressure. The gasoline and water will separate, but the water

and ethyl alcohol within the gasoline will mix. This water/alcohol

mix will settle separately at the bottom of the flask. (Water is

heavier than gasoline, and alcohol is heavier than water.)

5. Note the numbered level at which the water/alcohol mix has

settled within the flask. Subtract 20 from this number


(representing the 20 mL of water you added earlier). This amount

equals the percentage of alcohol found in this gasoline.

6. Dispose of the gasoline in accordance with local, state, and

federal regulations.

Alternative Fuels

Chapter 67 identifies the alternative fuels used with and in place of

gasoline and discusses how they affect driveability. This chapter also

explains how alternative fuels reduce carbon monoxide (CO) exhaust

emissions and safety precautions for working with alternative fuels.

The following videos and animation links from the author’s website will

help you better understand the textbook and your assignments.

Alternative Fuel (www.jameshalderman.com/links/book_at/vid/ch

67/video_frame.html)

Fuel Mileage and Range, Electric (jameshalderman.com/links/a8/

html5/fuel_mileage_electric.html)

Fuel Mileage and Range, Electric Extended Range, EREV (jame

shalderman.com/links/a8/html5/fuel_mileage_erev.html)

Professional Opportunities

Visit a local auto repair shop and ask the customer service technician

the following questions:

What types of work are available there?

What are the training and qualification requirements?



http://jameshalderman.com/links/a8/html5/fuel_mileage_electric.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_erev.html

What’s the approximate salary range for a technician trained in

automotive fuel systems?

If visiting a repair shop isn’t convenient for you, search the Internet for

the same information.

Personal protection equipment should be used when handling

methanol. Be sure to find out the required safety precautions for

handling this material.

Diesel And Biodiesel Fuels

Chapter 68 explains diesel fuel specifications and shows the

advantages and disadvantages of biodiesel. American Petroleum

Institute (API) gravity is defined and E-diesel is explained.


help you better understand the textbook and your assignment.

Diesel Fuel (www.jameshalderman.com/links/book_at/vid/ch68/vi

deo_frame.html)

Cetane

The cetane number is a measure of the ignition quality of diesel fuel,

or how easily the fuel can be ignited. Cetane numbers generally range

between 45 and 50. Higher cetane numbers indicate good ignition

quality, resulting in only a short delay period between injection and

ignition. Conversely, lower cetane numbers indicate poorer ignition



quality, which results in a longer delay period. Long delays can cause

hard starting, often resulting in white smoke and engine misfires.

Think of the cetane number as being the opposite of an octane

number for gasoline. Octane numbers are a measure of how slowly

the fuel ignites, or its resistance to self-ignition.

Search the Internet to find how the specific gravity of diesel fuel is

measured.

Key Points and Links

READING ASSIGNMENT

Key Points

When a rich mixture is detected and the fuel gauge reads full,

you should check the charcoal canister outlet to the engine for

blockage. This will verify whether liquid gas is being sucked into

the engine.

Personal protection equipment should be used when handling

methanol.

The cetane number is a measure of the ignition quality of diesel

fuel, or how easily the fuel can be ignited.

Cetane numbers generally range between 45 and 50.

Higher cetane numbers indicate good ignition quality, resulting in

only a short delay period between injection and ignition.

Conversely, lower cetane numbers indicate poorer ignition

quality, which results in a longer delay period.


Links

Gasoline (www.jameshalderman.com/links/book_at/vid/ch66/vide

o_frame.html)

In-Line Fuel Blending (jameshalderman.com/links/a8/html5/Fuel_

Blending_In-Line-Chapter_66-A8.html)

Sequential Fuel Blending (jameshalderman.com/links/a8/html5/F

uel_Blending_Sequential-Chapter_66-A8.html)

Splash Fuel Blending (jameshalderman.com/links/a8/html5/Fuel_

Blending_Splash-Chapter_66-A8.html)

Fuel Mileage and Range, Gasoline (jameshalderman.com/links/a

8/html5/fuel_mileage_gas.html)

Fuel Mileage and Range, Hybrid (jameshalderman.com/links/a8/h

tml5/fuel_mileage_hybrid.html)

Alternative Fuel (www.jameshalderman.com/links/book_at/vid/ch


Fuel Mileage and Range, Electric (jameshalderman.com/links/a8/

html5/fuel_mileage_electric.html)

Fuel Mileage and Range, Electric Extended Range, EREV (jame

shalderman.com/links/a8/html5/fuel_mileage_erev.html)

Diesel Fuel (www.jameshalderman.com/links/book_at/vid/ch68/vi

deo_frame.html)

Engine Fuels

1. The pressure of gasoline vapor in a closed container measured at



http://jameshalderman.com/links/a8/html5/Fuel_Blending_In-Line-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/Fuel_Blending_Sequential-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/Fuel_Blending_Splash-Chapter_66-A8.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_gas.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_hybrid.html


http://jameshalderman.com/links/a8/html5/fuel_mileage_electric.html

http://jameshalderman.com/links/a8/html5/fuel_mileage_erev.html


100 °F is known as _________.

2. ________ is a condition in which vapors get into the fuel system;

this can result in poor engine performance.

3. Technician A says that spark knock, ping, and detonation are

different names for abnormal combustion. Technician B says that

any abnormal combustion raises the temperature and pressure

inside the combustion chamber and can cause severe engine

damage. ________ is/are correct.

a. Technician A

b. Technician B

c. Both Technicians A and B

d. Neither Technicians A nor B

4. E85 fuel is

a. 85% gasoline and 15% ethanol.

b. 85% ethanol and 15% gasoline.

c. ethanol that’s 15% water.

d. pure ethyl alcohol.

5. Which of the following is the most widely used alternative fuel?

a. E85

b. Propane

c. Syn-gas

d. M85

6. The low-temperature point at which the waxes in diesel fuel tend

to form crystals is known as the _______.

7. Ultra-low-sulfur diesel fuel contains less than _______ parts per

million (ppm) of sulfur.


8. The specific gravity of diesel fuel is measured in _______.

a. hydrometer units.

b. API gravity units.

c. octane numbers.

d. cetane numbers.

9. The _______ rating of diesel fuel indicates how well a diesel

engine will start with that fuel.

a. specific gravity

b. sulfur content

c. cloud point

d. cetane

Exercise Answer Key:

Engine Fuels

1. Reid vapor pressure

2. Vapor lock

3. c

4. b

5. b

6. cloud point

7. 15

8. b

9. d


1.2 Describe the fundamentals, diagnosis, and serviceof engine ignition systemsIgnition System

READING ASSIGNMENT

Read this assignment. Then read Chapter 69 and 70 in your textbook.

Ignition System Components and Operation

Chapter 69 explains how the ignition system and ignition coils work

and discusses the operation of the crankshaft position sensor, the

pickup coil, and the distributor ignition. Newer ignition systems like

waste-spark and coil-on-plug (COP) are explained along with knock

sensors and ignition control circuits.


help you better understand the textbook and your assignment.

Ignition Systems (www.jameshalderman.com/links/book_at/vid/ch


Hall-Effect Sensor (jameshalderman.com/links/a8/html5/Hall-effe

ct_Sensor-Chapter_70-A8.html)

Waste Spark Ignition System (jameshalderman.com/links/a8/html

5/wast_spark_ignition_operation.html)

Cylinder Deactivation System (jameshalderman.com/links/a8/htm

l5/Cylinder_Deactivation_Sys-Chapter_32-A1_and_A8.html)

Coil-On-Plug Ignition System (jameshalderman.com/links/a8/html

5/coil_on_plug_operation.html)



http://jameshalderman.com/links/a8/html5/Hall-effect_Sensor-Chapter_70-A8.html

http://jameshalderman.com/links/a8/html5/wast_spark_ignition_operation.html

http://jameshalderman.com/links/a8/html5/Cylinder_Deactivation_Sys-Chapter_32-A1_and_A8.html

http://jameshalderman.com/links/a8/html5/coil_on_plug_operation.html

Never check for sparks by pulling a plug wire on a running engine. In

addition to risking personal injury, you could damage or shorten the

life of electronic ignition components.

Identifying Ignition Systems

You’ll need to be able to identify ignition systems on various types of

vehicles. To practice, gain permission to access five different vehicles.

Based on what you learned in this chapter, identify the ignition system

used in each.

BUILDING AN IGNITION COIL

The next two exercises will help you understand how the ignition

system and ignition coils work. Begin by reviewing pages 782–783 in

your textbook.

An ignition coil is basically a step-up transformer that works through

electromagnetic induction. It uses one winding (coil), the primary, to

induce or step up the voltage in a secondary winding.

Materials:

2 polyvinyl chloride (PVC) plumbing pipes—1⁄2-inch diameter and

1-inch diameter, both about 7 inches long, as shown in "PVC

Pipes"

70 feet of 16-gauge copper wire

210 feet of 32-gauge copper wire


1 12-volt battery supply

1 DMM (digital multimeter)

1 roll of electrical tape

PVC Pipes

PVC Pipes (Courtesy of Dr.

John Kershaw)

Steps:

1. Wrap 50 turns of 16-gauge wire around the larger 1-inch PVC

pipe. Use electrical tape to hold the wire in place. This will serve

as the primary winding.

2. Wrap 150 turns of 32-gauge wire around the ½-inch PVC pipe.

Use electrical tape to hold this wire in place as well. This will

serve as the secondary winding.

3. Place the ½-inch PVC pipe winding inside the 1-inch PVC pipe

winding.

4. Connect your DMM to the primary winding.

5. Hook up the 12-volt power supply to the primary winding leads.

6. Close the power supply switch and read the secondary winding


voltage.

7. Record the voltage at the secondary winding: ______

8. Open the power supply switch and then close it again. Describe

what happened to the voltage.

9. Which voltage was greater, the primary or the secondary?

BUILDING AND TESTING A TRANSISTOR SWITCH

Materials:

1 breadboard and jumper wire kit

1 battery, 9-volt

1 TP31 NPN transistor

1 package of 12-volt mini lamps (3)

2 STSP switches

1 package of mini low-voltage LEDs (red)

1 package of heavy duty 9-volt snap connectors

Transistor Switching Circuit Wiring Diagram


Transistor Switching Circuit Wiring Diagram

Transistor Switching Circuit Build


Transistor Switching Circuit Build (Courtesy of Dr. John

Kershaw)

Steps:

1. Build the circuit shown in the next two figures on the circuit

breadboard using the transistor, two switches, filament bulb (mini

lamp), and red LED.

2. Turn Switch 1 and then Switch 2 to the on position.

Conclusion:

The LED and mini lamp should be lit, demonstrating that the transistor

is providing the switch to ground. This parallels the way the transistor

would provide the switch to ground for a primary ignition coil.


Ignition System Diagnosis and Service

Chapter 70 covers the servicing and testing of engine ignition

systems, specifically spark tester use, ignition spark testing and

ignition sensor testing. You’ll learn about the construction and

operation of different types of spark plugs and how to inspect the

spark-plug wire. You’ll also study the steps necessary to check and

adjust ignition timing on engines equipped with a distributor, and you’ll

learn how to diagnose an engine that doesn’t start as well as how to

test with an ignition scope.


help you better understand the textbook and your assignments:

Ignition Service (www.jameshalderman.com/links/book_at/vid/ch7

0/video_frame.html)

Test Spark Plug Wire (jameshalderman.com/links/a8/html5/test_s

park_plug_wire_ch70.html)

Always do a careful visual inspection of coil housing. This will help you

locate burn marks or cracks that indicate a faulty coil.

Search the Internet to find out what safety precautions should be

taken when working with and testing ignition system components to

avoid electrical shock. An example of this would include: Do not hold

or touch a spark tester while checking for spark.

The reach of a spark plug is the length of its metal-threaded area. Be



http://jameshalderman.com/links/a8/html5/test_spark_plug_wire_ch70.html

sure to check the reach of any spark plugs being installed. Putting in

plugs with the wrong-sized reach may cause engine damage.

TESTING AN IGNITION PICK-UP COIL

This task will help you understand the use of a spark tester as well as

the procedure for ignition spark testing and ignition sensor testing.

Start by reviewing pages 796–798 in your textbook.

Materials:

1 used ignition pick-up coil of any type (such as the high-energy

ignition unit shown)

1 DMM

Checking the Resistance of an Ignition Pick-up Coil


Checking the Resistance of an Ignition Pick-up Coil

(Courtesy of Dr. John Kershaw)

Steps:

1. Set your DMM on the 2,000 ohms (Ω) position.

2. Measure the resistance of the pick-up coil by placing the red lead

on one of the coil leads and the black lead on another.

3. Compare your DMM results with those

in the figure.

Conclusion:

The reading on the face of the meter is 797 ohms, which ranges

roughly in the middle of the 500- to 1,500-ohm specifications for that


component. This tells you that the coil is working properly.

TESTING A SPARK PLUG WIRE

This task will help you learn how to inspect the spark plug wire. Begin

by reviewing pages 799–801 in your textbook.

Testing the Resistance of a Spark Plug Wire

Testing the Resistance of a Spark Plug Wire (Courtesy of

James Halderman)

Steps:

1. Remove a spark plug wire from your vehicle without damaging

the ends.


2. Set your DMM on 2,000 Ω (or 20 on the kΩ scale) and connect

the red and black leads as shown in the figure.

3. Compare your results with those in the figure.

Conclusion:

When measuring the resistance of a spark plug wire with a multimeter

set to the ohms position, the reading of 16.03 kΩ (roughly 16,000

ohms) shown in "Testing the Resistance of a Spark Plug Wire" would

be acceptable because the wire is about two feet long. A standard

reading is 10 kΩ per 10 feet. Thus, the maximum allowable resistance

for a two-foot spark plug wire would be 20 kΩ (20,000 ohms).

Key Points and Links

READING ASSIGNMENT

Key Points

Safety is paramount when working with any fuel system. Make

sure you know and understand the operation of the ignition

system you’re working on to be safe and perform an accurate

repair.

Always make a careful visual inspection of the ignition system;

this will help to locate burn marks or cracks that indicate a faulty

coil or other ignition components.

Links

Ignition Systems (www.jameshalderman.com/links/book_at/vid/ch




Hall-Effect Sensor (jameshalderman.com/links/a8/html5/Hall-effe

ct_Sensor-Chapter_70-A8.html)

Waste Spark Ignition System (jameshalderman.com/links/a8/html

5/wast_spark_ignition_operation.html)

Cylinder Deactivation System (jameshalderman.com/links/a8/htm

l5/Cylinder_Deactivation_Sys-Chapter_32-A1_and_A8.html)

Coil-On-Plug Ignition System (jameshalderman.com/links/a8/html

5/coil_on_plug_operation.html)

Ignition Service (www.jameshalderman.com/links/book_at/vid/ch7

0/video_frame.html)

Test Spark Plug Wire (jameshalderman.com/links/a8/html5/test_s

park_plug_wire_ch70.html)

Ignition System

1. Battery voltage is increased to 40,000 volts in the ignition coil by

pulsing the primary windings on and off to ground through the

module. The _________ around the primary winding induces the

high-voltage change in the adjacent secondary winding.

2. A _________ produces a varying voltage when the notch on the

camshaft or crankshaft passes near the sensor and changes the

strength of the _________ around the sensor.

3. What type of switch reacts to a magnetic field and produces an

output voltage signal?

4. A compression-sensing ignition system uses a ________-type


http://jameshalderman.com/links/a8/html5/Hall-effect_Sensor-Chapter_70-A8.html

http://jameshalderman.com/links/a8/html5/wast_spark_ignition_operation.html

http://jameshalderman.com/links/a8/html5/Cylinder_Deactivation_Sys-Chapter_32-A1_and_A8.html

http://jameshalderman.com/links/a8/html5/coil_on_plug_operation.html


http://jameshalderman.com/links/a8/html5/test_spark_plug_wire_ch70.html

ignition.

a. distributor

b. coil-on-plug

c. waste-spark

d. None of these options

5. Technician A says that a two-wire COP system uses the

powertrain control module (PCM) to trigger the coil. Technician B

says that a three-wire COP system has an ignition control module

(ICM) built into the coil assembly. _______ is/are correct.

a. Technician A

b. Technician B


d. Neither Technician A nor B

6. A ________ is the preferred tool for checking ignition system

operation because it loads the ignition coil and forces it to

produce at least 25,000 volts.

7. The slope of the ________ can indicate the air-fuel mixture

present in the cylinder as well as possible engine faults.

8. Technician A says that a pickup coil can be tested with an

ohmmeter. Technician B says that ignition coils can be tested

with an ohmmeter. _______ is/are correct.

a. Technician A

b. Technician B



9. Technician A says that a defective spark plug wire can cause an


engine misfire. Technician B says that corroded terminals on a

waste-spark coil can cause an engine misfire. _______ is/are

correct.

a. Technician A

b. Technician B



Exercise Answer Key:

Ignition System

1. collapsing magnetic field

2. magnetic sensor, magnetic field

3. A Hall-effect switch

4. c

5. c

6. spark tester

7. spark line

8. c

9. c

Lesson 1 Review

Self-Check


1. What characteristic of gasoline describes how easily it evaporates?

a. Purity

b. Driveability

c. Volatility

d. Octane rating

2. What is the minimum required octane rating for a gasoline to qualify

as "premium?"

a. 93

b. 91

c. 89

d. 87

3. What does it mean if a fuel pump at a station is labeled as E10?

a. The fuel is made up of 10% ethanol and 90% oxygen.

b. The fuel is made up of 90% ethanol and 10% gasoline.

c. The fuel is made up of 10% ethanol and 90% gasoline.

d. The fuel is made up of 10% oxygen and 90% ethanol.

4. What is the impact on fuel economy when using E85 instead of

gasoline?

a. The fuel economy is reduced by 20% to 30% when using E85.

b. The fuel economy is increased by about 5% when using E85.

c. The fuel economy is increased by 20% to 30% when using E85.

d. The fuel economy is reduced by about 5% when using E85.

5. Which alternative fuel is typically used in forklifts and other

equipment used inside warehouses, as the exhaust created is not

harmful?

a. Propane


b. Liquefied natural gas

c. Ethanol

d. Methanol

6. What does a yellow gas cap indicate?

a. The vehicle is a hybrid that requires fuel with a minimum octane

rating of 89.

b. The vehicle requires regular unleaded gasoline.

c. The vehicle is a flex-fuel vehicle that can use E85.

d. The vehicle requires diesel fuel and cannot run on regular

gasoline.

7. What color is diesel fuel dyed if it is intended for use on the streets

and highways?

a. Red

b. Green

c. Blue

d. Yellow

8. What characteristic of diesel fuel indicates how well a diesel engine

will start?

a. Pour point

b. Sulfur content

c. Cetane rating

d. Cloud point

9. What is the defining quality of biodiesel?

a. It is renewable fuel manufactured from vegetable oils, animal

fats, or restaurant greases.

b. It is diesel that contains up to 15% ethanol, and is also known


as diesohol.

c. It is intended for use by large machinery rather than automobiles

because of its toxicity.

d. It has a red tint and is intended specifically for farm use and off-

road use only.

10. Which type of alternate fuel is comprised of at least 93% methane

once it's processed?

a. Compressed natural gas

b. P-series fuel

c. Propane

d. Ethanol

11. What is the defining quality of a waste-spark ignition system?

a. It is an electronic ignition system that uses a distributor.

b. It uses one ignition coil to fire the spark plugs for two cylinders at

the same time.

c. It uses a mechanically opened set of contact points to make and

break the electrical connection to ground.

d. It uses a single ignition coil for each cylinder with the coil placed

above or near the spark plug.

12. What is the firing order determined by?

a. The primary and secondary windings that surround the ignition

coil

b. The crankshaft and camshaft design and the location of the

spark plug wires

c. The triggering device that signals the switching of the coil on and

off


d. The type of sensor being used as the ignition switching device

13. What is a knock sensor used to detect?

a. Poor suspension

b. Spark plug failure

c. Abnormal combustion

d. Improper firing order

14. Which of the following is the most accurate physical description of

an ignition coil?

a. A core of soft iron surrounded by a secondary winding of thicker

wires, which is surrounded by a primary winding of very many thin

wires

b. A core of soft iron surrounded by a secondary winding of very

fine wires, which is surrounded by a primary winding of heavier wires

c. A core of soft iron surrounded by a primary winding of thicker

wires, which is surrounded by a secondary winding of thinner wires

d. A solid rubber core surrounded by a primary winding of heavy

wires, which is encased in a secondary winding of thinner wires

15. What device is responsible for signaling the switching of the coil on

and off, or just on in most instances?

a. Distributor

b. Trigger

c. Generator

d. Spark plug

16. An electronic spark tester has a specified gap that requires a

minimum of _______ volts to fire.

a. 25,000


b. 35,000

c. 40,000

d. 15,000

17. You're using a multimeter to test the resistance of a pickup coil.

What range of values would indicate that it's working correctly?

a. 50–150 ohms

b. 500 to 1,500 ohms

c. 1,500 to 3,000 ohms

d. 0–50 ohms

18. What can you tell about a spark plug that has a long ceramic

insulator path?

a. It will be less reactive to oxygen and therefore will not erode

away as easily.

b. It will typically have a longer service life and will be much less

prone to misfiring.

c. It is very likely to run hotter at the tip than a spark plug that has a

shorter path.

d. It will be significantly cooler at the tip than a spark plug that has a

shorter path.

19. What does an upward-sloping spark line usually indicate?

a. The spark plug is gapped too wide

b. An excessively rich air-fuel mixture

c. High secondary ignition system resistance

d. A mechanical engine problem

20. When analyzing an ignition oscilloscope pattern, what are the tall

vertical spikes on the chart referred to as?


a. Transistor-on points

b. Dwell sections

c. Firing lines

d. Spark lines

Self-Check Answer Key

1. Volatility

Explanation: Volatility describes how easily the gasoline forms a

vapor, assuming that the vapors will remain in the fuel tank or

fuel line and will cause a certain pressure based on the

temperature of the fuel.

Reference: Section 1.1

2. 91

Explanation: For a gasoline to be considered Premium grade, it

must have an octane rating of 91. "Regular" gasoline has an

octane rating of 87, and "Plus" has an octane rating of 89.


3. The fuel is made up of 10% ethanol and 90% gasoline.

Explanation: Ethanol (ethyl alcohol) is an oxygenated fuel

additive and is usually made from grain. Most automobile

manufacturers permit up to 10% ethanol if driveability problems

are not experienced.



4. The fuel economy is reduced by 20% to 30% when using E85.

Explanation: E85 (85% ethanol and 15% gasoline), has a high

octane rating but contains less heat energy compared to gasoline

or E10. The fuel economy is reduced by 20% to 30% if E85 is

used instead of gasoline.


5. Propane

Explanation: Propane is the most widely used of all of the

alternative fuels. It is often used in forklifts and other equipment

used inside warehouses and factories because the exhaust from

the engine using propane is not harmful.


6. The vehicle is a flex-fuel vehicle that can use E85.

Explanation: There are vehicles designed to run on E85 fuel,

composed of 85% ethanol and 15% gasoline. There are many

ways to identify such vehicles, and one such indication is a yellow

gas cap that indicates the car should use E85 fuel.


7. Green

Explanation: Diesel fuel that is intended for use on the streets

and highways is clear or green in color. By contrast, diesel

fuel that is intended for use on farms and for off-road use is dyed


red.


8. Cetane rating

Explanation: The cetane number is a measure of the ease with

which the fuel can be ignited. The cetane rating of diesel fuel

should be between 45 and 50. The higher the number, the more

easily the fuel is ignited.


9. It is renewable fuel manufactured from vegetable oils, animal fats,

or restaurant greases.

Explanation: Biodiesel is a renewable fuel that can be

manufactured from vegetable oils, animal fats, or recycled

restaurant greases. It is safe, biodegradable, and reduces serious

air pollutants such as carbon monoxide and hydrocarbons.


10. Compressed natural gas

Explanation: Compressed natural gas is nontoxic, odorless, and

colorless in its natural state. Once it's processed, it is at least

93% methane. Because the natural gas has to be compressed to

about 3,000 PSI or more, the weight and the cost of the storage

container is a major factor.



11. It uses one ignition coil to fire the spark plugs for two cylinders at

the same time.

Explanation: Electronic Ignition (EI) systems are ignition systems

that do not use a distributor. A waste-spark system is a type of EI

system that uses one ignition coil to fire the spark plugs for two

cylinders at the same time.


12. The crankshaft and camshaft design and the location of the spark

plug wires

Explanation: Firing order means the order that the spark is

distributed to the correct spark plug at the right time. The firing

order of an engine is determined by crankshaft and

camshaft design and the location of the spark plug wires in the

distributor cap of an engine equipped with a distributor.


13. Abnormal combustion

Explanation: Knock sensors are used to detect abnormal

combustion, sometimes also ping, spark knock, or detonation.

Abnormal combustion creates a vibration in the engine block, and

the knock sensor detects this and retards the ignition timing to

reduce the knock and the damaging effects it would cause to the

engine parts.



14. A core of soft iron surrounded by a secondary winding of very fine

wires, which is surrounded by a primary winding of heavier wires

Explanation: The center of an ignition coil contains a core of

laminated soft iron. It is surrounded by a secondary winding

of 20,000 turns of fine wire, thinner than human hair. This is

surrounded by a primary winding of approximately 150 turns of

heavy wire.


15. Trigger

Explanation: The device that signals the switching of the coil on

and off or just on in most instances is called the trigger. A trigger

is often a pickup coil in some distributor-type ignitions and a

crankshaft position sensor on electronic systems.


16. 25,000

Explanation: If the engine doesn't start, the first step should be to

check for secondary voltage out of the ignition coil or to the spark

plugs. A spark tester has a specified gap that requires at least

25,000 volts (25 kV) to fire.


17. 500 to 1,500 ohms

Explanation: A pickup coil or magnetic sensor contains a coil of

wire, and the resistance of this coil should be within the range


specified by the manufacturer. The resistance is usually between

150 and 1,500 ohms, but the service information will provide

exact specifications.


18. It is very likely to run hotter at the tip than a spark plug that has a

shorter path.

Explanation: The heat range of the spark plug indicates how

quickly the heat created at the tip is transferred to the cylinder

head. A plug with a long ceramic insulator path will run hotter at

the tip than a spark plug that has a shorter path because the heat

must travel farther.


19. A mechanical engine problem

Explanation: An upward-sloping spark line usually indicates a

mechanical engine problem or a lean air-fuel mixture. By

contrast, a downward-sloping spark line usually indicates high

secondary ignition system resistance or an excessively rich air-

fuel mixture.


20. Firing lines

Explanation: The leftmost vertical (upward) line in an ignition

oscilloscope pattern is called the firing line. Firing lines should be

about equal in length. A short line indicates low resistance in the


wire, while a high line indicates high resistance in the wire.


Flash Cards

1. Term: Gasoline

Definition: A complex mixture of various hydrocarbons refined from

crude petroleum oil for use as a fuel in engines

2. Term: Cracking

Definition: A process whereby hydrocarbons with higher boiling

points are broken down into lower-boiling hydrocarbons by exposing

them to very high temperatures

3. Term: Volatility

Definition: A measure of how easily the gasoline evaporates (forms a

vapor)

4. Term: Air-fuel Ratio

Definition: The proportion by weight of air to gasoline that the

injection system mixes as needed for engine combustion. It typically

ranges from 8:1 to 18.5:1.

5. Term: E10

Definition: A fuel blend made up of 10% ethanol and 90% gasoline


6. Term: Methanol

Definition: A light, volatile, colorless, tasteless, flammable, poisonous

liquid with a very faint odor. It is used as an antifreeze, a solvent, and

a fuel.

7. Term: Propane

Definition: The most widely used alternative fuel. It is normally a gas,

but is easily compressed into a liquid and stored in inexpensive

containers.

8. Term: Diesel

Definition: A fuel that contains more heat energy than gasoline, is

cleaner than gasoline, and is ignited by heat generated by high

compression rather than by a spark

9. Term: Cetane Number

Definition: A measure of the ease with which the fuel can be ignited.

It determines to a great extent the fuel's ability to start the engine at

low temperatures.

10. Term: E-diesel

Definition: Standard No. 2 diesel fuel that contains up to 15%

ethanol, also known as diesohol

11. Term: Switching

Definition: The function of turning the primary circuit on and off


12. Term: Hall-effect Switch

Definition: Switch that uses a stationary sensor and rotating trigger

wheel, and requires a small input voltage to generate an output or

signal voltage

13. Term: Distributor

Definition: Component that distributes the high-voltage spark from

the secondary terminal of the ignition coil to the spark plugs for each

cylinder

14. Term: Coil-on-Plug (COP) Ignition

Definition: Ignition system that uses one ignition coil for each spark

plug

15. Term: Waste-spark System

Definition: Ignition system uses one ignition coil to fire the spark

plugs for two cylinders at the same time

16. Term: Reach

Definition: The length of the threaded part of the plug

17. Term: Ignition Timing

Definition: The time that the spark plug fires in relation to piston

position


18. Term: Dwell

Definition: The amount of time that the current is charging the coil

from the transistor-on point to the transistor-off point


Documents

Fuels and Ignition Systems Automotive Repair …...Automotive Repair Technician 5 : Engine Fuels and Ignition Systems Lesson 1 Overview In this lesson, you'll cover gasoline, alternative