Automotive (level 3) > Ignition Systems > Flashcards

Ignition Systems Flashcards

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1
Q

What is the purpose of the ignition system?

A

To advance or retard the timing of a high energy spark (dependent on engine load and RPM) to ignite the air/fuel mixture

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2
Q

What is the purpose of an ignition coil?

A

Converts low voltage to high voltage

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3
Q

What is a step-up transformer?

A

Ignition Coil

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4
Q

How many coils are in the Primary ignition coil?

A

100-200

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5
Q

How many coils are in the Secondary ignition coil?

A

20,000-30,000

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6
Q

What type of wire is used in a Primary ignition coil?

A

Heavier wire (20-gauge)

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7
Q

How much voltage is used in a Primary ignition coil?

A

12 Volts

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8
Q

What type of wire is used in a Secondary ignition coil?

A

Finer wire

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9
Q

How many coils are used in the secondary coil in comparison to the primary?

A

100 – 250 times the primary

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10
Q

What is located at the center of an ignition coil, and what is its purpose?

A

soft iron core to create an electromagnetic field

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11
Q

How does an ignition coil work?

A

Current flows through the primary windings to form a magnetic field. Current then stops flowing through the primary winding and collapses the magnetic field, inducing the secondary windings and multiplying the voltage

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12
Q

What is the average ratio between Primary and Secondary ignition windings?

A

250:1

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13
Q

What 3 things control coil output?

A

1) current flow in primary coil
2) number of turns of wire in secondary coil
3) speed of the flux change of the magnetic field

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14
Q

what is Dwell?

A

The amount of time a coil has to build a Magnetic Field

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15
Q

as engine RPM increases, what happens to Dwell time?

A

Dwell time gets shorter

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16
Q

What can insufficient dwell can cause?

A

weak or no spark

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17
Q

What is it called, when a coil generates its maximum magnetic field strength?

A

Saturated (fully charged)

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18
Q

What happens to the secondary coils output, when increased current flows through the primary coil?

A

output will not increase

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19
Q

How much voltage is needed is needed to jump the gap in the spark plug?

A

roughly 10,000 volts

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20
Q

How much voltage can be in the secondary ignition coil?

A

up to 100,000 volts

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21
Q

How much voltage can be in the primary ignition coil?

A

battery voltage (12v)

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22
Q

What are the components of the primary distributer system?

A

Distributor cam
Ignition switch
Ignition Coil
Ballast resistor
Breaker Points

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23
Q

What are the components of an breaker point distributer style secondary ignition system?

A

Distributor cap
Ignition coil
Coil wire
Rotor
Spark plug wires
Spark plugs

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24
Q

What is a Ballast Resistor?

A

Reduces voltage supplied to the coil

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25
What is the Breaker point on a distributor?
A movable, spring loaded set of contacts that switches current flow to the coil
26
How many cam lobes are on a distributer?
1 lobe per cylinder
27
What is a condenser used for in mechanical ignition system?
absorbs high voltage spikes & prevents them from feeding back into the circuit
28
How much resistance does an ignition wire have?
1,000 ohms per foot
29
What is the purpose of distributor rotor?
Receives power from the ignition coil & distributes it to each individual cylinder
30
How fast does a distributor rotor spin?
camshaft speed (half of engine speed - RPM)
31
What is Advanced timing?
where the spark event happens sooner in relationship to the piston reaching top dead center
32
What is Retarded timing?
When the spark event happens later in relationship to the piston reaching top dead center
33
What does 'ATDC' mean?
After top dead center
34
What does 'BTDC' mean?
Before top dead center
35
What is another name for ATDC?
Advanced timing
36
What is another name for BTDC?
Retarded timing
37
What varies spark timing?
engine load engine temp. air/fuel charge temp. octane rating engine speed
38
What degree should the distributor be adjusted to?
8-15 degrees BTDC
39
What is vacuum advance?
manifold vacuum is applied to the distributor & a diaphragm would advance the ignition timing
40
What is mechanical advance?
as the distributor spins faster, a set of weights move outwards & add additional timing advance (centrifugal force)
41
What type of engine advancing only occurs at idle, light load & cruising speeds?
vacuum advance
42
What type of engine advancing only occurs at higher load and acceleration?
mechanical advance
43
At what RPM does mechanical advance operate?
1500-1800 RPM
44
By how many degrees can a timing light be advanced or retarded?
0.1 degree increments
45
What is the heat range of a spark plug?
400-800 celcius
46
What is preignition?
air/fuel charge is ignited before the spark plug, causing cylinder pressure to increase while the piston is still moving upwards
47
What can cause preignition?
Excessive engine temperatures Glowing exhaust valves Glowing spark plugs Carbon build up
48
What is detonation?
air/fuel ratio explodes in a cylinder or 2 flame fronts (spark & preignition) collide in a cylinder
49
What is the companion cylinder #3 if the firing order is 1-8-4-3-6-5-7-2?
#2
50
As engine speed increases, what must happen to the timing of the spark event?
timing advances
51
How does a 'Magnetic Pulse' distributor operate?
Iron pieces on a rotating wheel are moved towards & away from a pickup coil inducing a analog A/C voltage
52
How does a 'Hall Effect' distributor operate?
generates a digital D/C voltage and a rotating shield with gaps protect the magnetic field from constantly coming in contact with sensor
53
How does a 'Photoelectric' distributor operate?
LED emits light at 3 million m/s through a shutter wheel with 360 slits in it (1 slit for each degree)
54
A pickup coil that uses a reluctor wheel to induce a voltage will create what kind of a output signal?
A/C current
55
What spark system uses 1 coil to fire 2 plugs?
Waste spark system
56
Why is high voltage needed to establish a spark across the gap of a spark plug?
Because of the high resistance of the air gap between the electrodes
57
What is the benefit of eliminating the spark plug wire in COP ignition systems?
Reduces electro magnetic induction & RFI Radio frequency interruption
58
Why are variable pitch resistor spark plug wires used?
Reduces the impedance of the wire
59
Which kind of signal does a magnetic style crank sensor produce?
Variable A/C signal
60
Which kind of signal does a hall effect style crank signal produce?
Square wave frequency signal
61
Which sensor does a misfire monitor use to determine misfires?
CKP sensor
62
Engine ignition timing is controlled by opening of which circuit?
Ignition primary circuit
63
What occurs when a knock sensor detects preignition and detonation in an engine?
Timing is retarded
64
What is used to reduce the voltage supplied to the ignition coil?
Ballast resistor
65
As engine RPM increases, what can happen to the voltage in the secondary ignition system?
Voltage can decrease at higher RPM due to a shorter amount of time the coil can build its magnetic field
66
Which winding in an ignition coil is finer/thinner?
Secondary winding
67
A vehicle has the points located on the ground side of the coil winding. When the engine is cranked there is a constant 12 volts present at both the positive and negative posts of the coils primary windings. What is the likely cause of this no start issue?
Points are stuck open
68
An ignition event ignites the air and fuel prematurely and the piston is exposed to excessive heat for longer than normal duration. This is known as?
Detonation
69
If the mechanical advance on an engine was stuck in the closed position and the weights could not move out, what condition would this cause?
Lack of Power
70
When checking engine timing with a timing light, where is the inductive pick-up placed?
Cylinder #1
71
When installing a distributor, how do you set cylinder #1 to top dead center compression?
Make sure the timing marks are aligned on the crankshaft and feeling for a rush of air through the spark plug hole when rotating the engine (compression)
72
How many degrees of rotation does the Camshaft make in a complete 4 stroke cycle?
360 degrees
73
What direction does a Distributor rotor rotate?
Depending on the manufacturer, they can rotate clockwise or counterclockwise
74
When referring to the total timing of an engine under load, what should a normal operating engine have at 3500+ RPM?
35 degrees
75
How does the PCM register a misfire?
by monitoring the acceleration and deceleration of the crankshaft
76
What is DIS?
Digital Ignition System; uses multiple coil packs instead of distributor, and a computer controlled timing that uses a CKP and CMS sensor for engine position
77
How does a Knock Sensor operate?
A Piezo-ceramic crystal creates small voltage when engine knock/detonation is transferred through the engine block. The PCM then reads this voltage signal and retards engine timing to prevent damage
78
A waste spark system will fire companion cylinder at the end of which strokes?
Compression & Exhaust strokes
79
If a coil driver for a waste spark system is located inside the PCM, what voltage would be expected at the PCM to be when the coil is building its magnetic field?
0.1 volts
80
Which ignition system has the longest coil dwell time?
DIS coil on plug
81
A misfire monitor is not functioning because the crankshaft adaptive numerator has been lost. How does a technician relearn this value?
Road test the vehicle to relearn
82
How is engine load calculated on a DIS system?
It monitors the Manifold absolute pressure sensor and the Throttle position sensor
83
What forms of stress testing are mentioned in the chapter 26?
Moisture, Heat and Cold
84
What is the procedure for checking a waste spark coil's secondary winding?
Measure between both secondary output posts
85
What are forms of trace pattern used when diagnosing an ignition system?
Firing, Spark and Dwell
86
When inspecting a spark plug, what are indicators that the plug has been overheated/ran too hot?
A light gray or white blistering of the electrodes
87
When diagnosing an ignition system fault that has not produced a DTC, what should be checked first?
input Signal
88
What does the spark line represent?
the time the spark actually lasts
89
What tool should be used to measure the air gap of the crankshaft or camshaft sensors
A non-magnetic feeler gauge
90
What does a cylinder performance/power balance test measure?
individual cylinders RPM drop
91
What can a hall effect cap sensor be checked with?
Voltmeter
92
What problem would a P0300 series code indicate?
misfiring cylinder
93
What problem would a P0200 series code indicate?
fuel injector system error
94
What condition requires more timing (additional advance) to obtain complete combustion?
deceleration/coasting
95
When a DIS waste spark system detects a misfire, what does the computer do to try and repair the misfire?
increases dwell time to deliver a higher output from the secondary winding
96
An ignition coil is being tested on a vehicle that will not start, there is 12 volts constant present on both sides of the coil when cranking, which of the following is the most likely fault with the information given?
faulty transistor
97
What are the 4 types of Spark Plug electrodes? (in order of service life)
Copper, Platinum, Iridium & Ruthenium
Automotive (level 3)
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