Deck 27: Ignition System Diagnosis and Service

Question 1

On an oscilloscope, which section ends with the primary coil current off signal?

A) intermediate
B) dwell
C) firing
D) both "intermediate" and "dwell"

Answer 1

B

Question 2

Detonation can cause physical damage to the pistons, valves, bearings, and spark plugs.

Answer 2

True

Question 3

An ignition control module may overheat if it is not securely mounted.

Answer 3

True

Question 4

Which of the following statements about carbon tracking is NOT correct?

A) Carbon tracking may occur inside a distributor cap
B) Carbon tracking indicates that high voltage has followed a low-resistance conductive path
C) Carbon tracking may cause a misfire
D) Carbon tracking usually occurs in the primary ignition circuit

Question 5

The reluctor (or pole piece) of a magnetic pulse generator should be replaced as a maintenance item when engine spark plugs are renewed.

Question 6

Damaged spark plug threads in an aluminum cylinder head cannot be repaired. The head must be replaced if the threads are damaged.

Question 7

A defective EI coil may cause cylinder misfiring.

Question 8

If a vacuum gauge shows a low but steady vacuum when the engine is at idle, the problem is a noncommon type.

Question 9

Gapping the spark plug is only necessary on used spark plugs. New spark plugs have their gaps set at the factory.

Question 10

A misfire is also called incomplete combustion.

Question 11

All ignition system diagnosis should begin with a visual inspection.

Question 12

Preignition is the same as detonation.

Question 13

A bad sensor ground may cause the same symptoms as a faulty sensor.

Question 14

Insufficient timing advance or retarded timing at higher engine speeds could cause hesitation and poor fuel economy.

Question 15

Which of the following is NOT a cause of spark knock?

A) excessively advanced ignition timing
B) engine overheating
C) excessively lean air/fuel mixture
D) high-octane fuel

Question 16

EMI can be produced by the vehicle's primary ignition circuit.

Question 17

An ignition module may be damaged due to a poor electrical ground circuit.

Question 18

All ignition system problems will set a DTC in the vehicle's PCM and can be read with a scan tool.

Question 19

Leaner air/fuel mixtures ______.

A) decrease the electrical resistance inside the cylinder and decrease the required firing voltage
B) increase the electrical resistance inside the cylinder and increase the required firing voltage
C) increase the electrical resistance inside the cylinder and decrease the required firing voltage
D) have no measurable effect on cylinder resistance

Question 20

Spark plug cables from consecutively firing cylinders should ______.

A) cross rather than run parallel to one another
B) run parallel rather than cross one another
C) cross and run parallel to one another
D) none of these answers is correct

Question 21

Ignition coil testing is being discussed. Technician A uses an ohmmeter to measure primary and secondary resistance. Technician B uses an oscilloscope and a test spark plug to measure maximum coil output voltage. Who is correct?

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

Question 22

A "cranks but does not start" problem on a waste spark type EI system is being diagnosed. When a spark tester is connected to each coil and the starter is engaged, there is no spark. Technician A says the crankshaft position sensor could be the problem. Technician B says the PCM could be the problem. Who is correct?

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

Question 23

Waste spark EI systems are being discussed. Technician A says a high-resistance spark plug can affect the firing of its companion spark plug. Technician B says improper spark plug torque can cause an engine misfire. Who is correct?

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

Question 24

A no-start condition on an EI system is being discussed. Technician A says to use a test spark plug to determine whether the problem is in the ignition system. Technician B says that if a noid light is connected to the injector harness and it pulses while the engine is cranked, the triggering unit for the primary ignition circuit should be okay. Who is correct?

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

Question 25

Possible causes for a no-start condition on a coil-over-plug EI engine are being discussed. Technician A says a faulty crankshaft sensor may prevent the engine from starting. Technician B says a shorted ignition coil may be the cause. Who is correct?

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

Question 26

During a coil output test, the firing line shown on the oscilloscope pattern should exceed ______ volts.

A) 12
B) 350
C) 1,200
D) 35,000

Question 27

Technician A performs a cylinder performance test [power balance test] to determine which cylinder is misfiring. Technician B uses a vacuum gauge to pinpoint the misfiring cylinder. Who is correct?

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

Question 28

Which of the following problems is NOT caused by a misfire?

A) lack of power
B) high idle speed
C) poor fuel economy
D) excess exhaust emissions

Question 29

Which of the following is NOT the location of the ignition module?

A) inside the distributor
B) underneath the coil packs
C) on the steering column, behind the ignition switch
D) integral with the PCM

Question 30

While testing a coil in an EI ignition system, Technician A says an infinite reading means that the winding has zero resistance and is shorted. Technician B says the secondary winding in a waste spark [doubled-ended] coil should be checked by connecting the meter across the two secondary terminals. Who is correct?

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

Question 31

Crankshaft position sensors [CKP] are _____ type sensors.

A) Hall-effect
B) magnetic pulse generators
C) both "Hall-effect" and "magnetic pulse generators"
D) neither "Hall-effect" nor "magnetic pulse generators"

Question 32

To minimize EMI interference, sensor wires should be routed away from _____.

A) spark plug wires
B) ignition coils
C) distributor caps
D) all answers are correct

Question 33

An ohmmeter connected to the leads of a pickup coil in a DI ignition system reads 14 ohms of resistance. The reading indicates that the pickup coil ______.

A) is satisfactory
B) is shorted
C) is open
D) has high resistance

Question 34

Technician A says large amounts of EMI can collapse the field in a coil and cause a plug to fire. Technician B says poor spark plug cable insulation may cause EMI. Who is correct?

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

Question 35

Spark plug firing voltage should normally be ______.

A) 7 to 13 kV
B) less than 3 kV
C) 3 to 13 kV
D) none of these answers is correct

Question 36

While discussing an ignition problem displayed on a scope primary ignition pattern, Technician A says a worn distributor drive gear can cause an erratic transistor ON signal. Technician B says if there are erratic voltage spikes at the transistor ON signal, the ignition module may be faulty. Who is correct?

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

Question 37

Test equipment for checking the primary circuit is being discussed. Technician A says a logic probe can be used. Technician B says a DMM can be used. Who is correct?

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

Question 38

The firing lines on an oscilloscope are all abnormally low. Technician A says the problem could be a faulty coil. Technician B says the problem could be a lean air/fuel mixture. Who is correct?

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

Question 39

While discussing EI service, Technician A says the crankshaft sensor may be rotated to adjust the basic ignition timing. Technician B says the crankshaft sensor may be moved to adjust the clearance between the pickup coil and reluctor on some EI systems. Who is correct?

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

Question 40

Technician A says a fouled spark plug can cause a misfire. Technician B says a bad coil can cause a misfire. Who is correct?

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

Question 41

Spark duration is represented by the length of the spark line and is measured in ____________________.

Question 42

Technician A says white or grayish powdery deposits on secondary cables at the point where they cross or near metal parts indicate that the cables' insulation is faulty. Technician B says if the spark plug wire for #2 cylinder is damaged and the other wires look good, replace only the damaged wire. Who is correct?

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

Question 43

The dwell period on a modern electronic ignition system ______.

A) is fixed and does not change with engine RPM
B) increases [lengthens] as engine RPM increases
C) decreases [shortens] as engine RPM increases
D) is required

Question 44

Technician A removes plug wires by grasping the spark plug boot and gently twisting it off. Technician B uses a 13/16 in. deep thinwall socket to remove spark plugs. Who is correct?

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

Question 45

Which of the following is not a common cause of preignition?

A) faulty ignition coil
B) incandescent carbon deposits in the combustion chamber
C) faulty cooling system
D) too hot of a spark plug

Question 46

An exhaust gas analyzer will show higher than normal ____________________ when ignition timing is not correct.

Question 47

What type of fouling occurs immediately following an overdue tune-up?

A) wet fouling
B) cold fouling
C) splash fouling
D) glazing

Question 48

Carbon ____________________ is the formation of a line of carbonized dust between distributor cap terminals or between a terminal and the distributor housing.

Question 49

Mode ____________________ scan tool data displays the test values stored at the time a particular monitor was completed. This data can be useful in engine misfire diagnosis.

Question 50

Noise symptoms of overly advanced timing include ____________________ or engine knock.

Question 51

If the spark line is totally flat, is longer than 2 ms, and is less than 500 volts, there is a good chance that:

A) the plug is not firing
B) the air/fuel ratio is excessively lean
C) there is high resistance in the spark plug wires
D) the spark plug heat range is wrong for the engine

Question 52

Usually an engine is timed so that the number 1 spark plug fires several degrees _____.

A) BTDC [before top dead center]
B) ATDC [after top dead center]
C) BBDC [before bottom dead center]
D) ABDC [after bottom dead center]

Question 53

Technician A says a loose ignition module mount can cause intermittent misfires or no-start conditions. Technician B says when installing a new ignition module, a small amount of heat conductive grease should be applied to the mounting surfaces. Who is correct?

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

Question 54

If a distributor cap or rotor has a mild buildup of dirt or corrosion, it should be ____________________.

Question 55

The air gap between the crankshaft position sensor [CKP] and the trigger wheel is measured with a(n) _____.

A) wire gauge
B) nonmagnetic feeler gauge
C) inside micrometer
D) dial indicator

Question 56

The height of the ____________________ line in a secondary oscilloscope pattern represents the amount of voltage needed to initiate a spark across the spark plug gap.

Question 57

An occasional glow around a spark plug cable, known as a ____________________ effect, is not harmful but indicates that the cable should be replaced.

Question 58

Most engines have a spark duration of approximately _____ milliseconds.

A) 0.5
B) 1.5
C) 5.0
D) 15.0

Question 59

An oscilloscope shows electrical ____________________ changes over a given period of time.

Question 60

Any hot spot within the combustion chamber can cause ____________________.

Question 61

Describe two important precautions that should be taken during all ignition system tests.

Question 62

Describe how to test the integrity of a suspect electrical connection.

Question 63

If the needle on a vacuum gauge drops significantly every two revolutions of the engine, the fault is a ____________________ problem.

Question 64

Only engines equipped with a ____________________ may need to have their ignition timing set or adjusted.

Question 65

Some manufacturers recommend the use of special heat-conductive ____________________ grease between the control unit [ignition module] and its mounting surface.

Question 66

Describe how to quick-check a knock sensor.

Question 67

The slope of the spark line is a good indication of the ____________________.

Question 68

What basic tools are used when checking a Hall-effect sensor?

Question 69

Name the three types of secondary circuit trace patterns available on an oscilloscope.

Question 70

Describe a cylinder performance (balance) test.

Question 71

Identify various drivability problems that an ignition system misfire can cause.

Question 72

Identify the appearance of a normal spark plug.

Question 73

What problems typically cause DTCs that indicate a misfire at an individual cylinder (P0301, P0302, P0303, etc.)?

Question 74

Name the three categories of stress tests used to check for intermittent ignition component problems.

Question 75

What is Mode #6 data?

Question 76

What is the first step in diagnosing an ignition system problem?

Question 77

What are the causes of detonation?

Question 78

Identify various concerns that may affect the height of spark plug firing lines.

Question 79

The companion cylinder for #1 cylinder on a six-cylinder engine with a firing order of 153624 is cylinder # ____________________.

Question 80

An engine may start with a faulty camshaft sensor, but it may only run in the ____________________ mode because the fuel injectors cannot be synchronized without the camshaft signal.