1
Q
Dwell refers to what?
A
The amount of time a coil is given to build a magnetic
field.
2
Q
How many more turns of coil does the secondary winding have compared to the primary winding of an ignition coil?
A
100 - 250 times more
3
Q
What is located at the center of the ignition coil?
A
An iron core
4
Q
What are the three factors that control the coil output?
A
The amount of current
Number of turns in the wire
Speed of the flux change
5
Q
The more dwell time a coil receives the ________________
A
Higher the voltage output
6
Q
What does coil saturation refer to?
A
When a coil generates its maximum magnetic field strength.
7
Q
What are the components of the primary ignition system?
A
Ignition switch
Ballast resistor
Breaker points
Distributor Cam
Ignition coil
8
Q
A ballast resistor is used to do what?
A
To reduce the voltage that is supplied to the ignition coil.
9
Q
What are breaker points?
A
Movable spring loaded set of contacts that switch the current flow to the coil
10
Q
What is a condenser and what is its role in the primary ignition system?
A
The condenser is a capacitor that prevents high voltage spikes from arcing backwards across the points and causing failure and wear.
11
Q
How many Volts are typical for the secondary ignition system?
A
Usually 30,000 but can reach up to 100,000 V
12
Q
What are the components of the secondary ignition system?
A
Ignition coil
Coil wire
Distributor Cap
Rotor
Spark plug wires
Spark plugs
13
Q
What’s the typical resistance for ignition cables?
A
1000 Ohms per foot
14
Q
Camshaft speed is _____________
A
Half of engine speed
15
Q
Explain advancing the timing
A
Where the spark event happens sooner in relationship to the piston reaching top dead center
16
Q
Explain retarding the timing
A
When the spark event happens later in relationship with the pistons position
17
Q
Spark timing varies depending on three things:
A
Load
Temp of engine
Temp of incoming air/fuel
18
Q
Base timing usually ranges from:
A
8-15 Degrees Before Top Dead Center (BTDC)
19
Q
When does vacuum advance operate?
A
At idle and low cruising speeds
20
Q
How does mechanical advance work?
A
By using centrifugal force, as it spins faster weights move outwards and add additional timing advance.
21
Q
When does mechanical advance operate?
A
Around 1500-1800 RPM
22
Q
Preignition is when:
A
The air fuel charge is ignited ahead of the spark plug.
23
Q
What are the causes of pre ignition?
A
Excessive engine temps
Glowing spark plugs
Carbon build up
Glowing exhaust valves
24
Q
What are the causes of detonation?
A
Low octane rating
Excessive Heat
Excessive pressures
Lack of cooling
25
As engine speed increases what must happen to the timing of the spark event?
It must advance
26
What type of device adds additional timing as engine speeds increase?
Mechanical Advance
27
What type of device adds additional timing under light load applications?
Vacuum advance
28
What could cause a hole that melted through the top of a piston?
Preignition
29
What are some disadvantages of a distributor?
More wearable components
One coil
Complicated mechanical operation
30
A pickup coil that uses a reluctor wheel to induce a voltage will create what kind of a output signal?
Alternating (A/C) current
31
Explain Dwell?
The time the coil is building the magnetic field in the primary winding
32
What operating condition is most reliant on ignition timing?
Engine speed
33
A spark system that uses one coil to fire 2 plugs is known as a?
Waste spark system
34
A magnetic pulse generator can also be used as a?
Speed sensor
Crank sensor
Camshaft sensor
35
What happens when the low voltage current through the coils primary winding is interrupted?
The magnetic field collapses and
a high voltage is induced into the coils secondary winding
36
What occurs when a spark plug with multiple ground electrodes is fired?
The spark will travel to the electrode offering the path of least resistance
37
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
38
What does the use of one coil per cylinder produce?
Greater coil saturation time
39
Reach, Heat range and and air gap are all characteristics that affect the performance of which ignition component?
Spark plugs
40
What is the benefit of eliminating the spark plug wire in COP ignition systems?
To reduce the chances of EMI (electro magnetic induction) and RFI (Radio frequency interruption).
41
Why are variable pitch resistor spark plug wires used?
To reduce the impedance of the wire
42
When does the magnetic field surrounding the coil in a magnetic pulse generator move?
When the reluctor tooth approaches the coil and when the reluctor tooth begins to move away
43
Which of the following electronic switching devices has a reluctor with wide shutter blades rather than teeth?
Hall effect sensor
44
A magnetic style crank sensor will give which kind of signal?
a variable a/c signal
45
A hall effect style crank signal will give which kind of signal?
Square wave frequency signal
46
A misfire monitor uses which sensor to determine misfires?
Crank sensor
47
Engine ignition timing is controlled by opening of which circuit?
Ignition primary circuit
48
A knock sensor is used to detect preignition and detonation in an engine. What occurs when a signal is received?
The timing is retarded
49
On a single coil distributor system what is used to reduce the voltage that is supplied to the coil?
Ballast resistor
50
What is the material used inside a ignition coil to strengthen the magnetic field?
Iron core
51
An ignition coil has a resistance of 1000 ohms between the primary positive and negative terminals. This is an indication that:
The resistance of the primary circuit is excessively high
52
The role of the breaker points in a points and condenser ignition system is to
Act as a switch that allows current to flow through the ignition coils primary winding
53
The term used for the amount of time the magnetic field has to build in an ignition coil is
Dwell
54
As engine RPM increases, what can happen to the voltage in the secondary system
Voltage can decrease at higher RPM due to a shorter amount of time the coil can build its magnetic field
55
Which winding in an ignition coil is finer/thinner
Secondary winding
56
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
57
To prevent coil overheating on a conventional points ignition system, manufacturers may
Lower the primary voltage in the run position to reduce current through the coil
58
As engine speed increases, the timing of the spark event must be
advanced
59
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?
Preignition
60
Detonation is the colliding of 2 flame fronts inside the combustion chamber, this can cause
A knocking or pinging sound Cracking of the piston ring lands
A broken or damaged spark plug
61
This component will advance the timing under light loads and steady engine operation (cruising speed).
Vacuum advance
62
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
63
Which of the following is a method manufacturers have implemented to cure LSPI on modern direct injection engines
Running a specific engine oil with special additives
64
When checking engine timing with a timing light, where is the inductive pick-up placed?
On cylinder number one wire
65
If the timing chain on an engine is stretched, how will this effect the ignition system
The spark event will be delayed (retarded)
66
A technician checks the timing on an engine and finds at idle it is 5 degrees before top dead centre. He needs to adjust it to the specification of 12 degrees before top dead centre. How does he change the base timing?
By rotating the distributor housing
67
A technician is going to install a distributor and needs to set the engine to top dead centre compression for cylinder #1. How is this done
By making sure the timing marks are aligned on the crankshaft
Feeling for a rush of air through the spark plug hole when rotating the engine (compression)
68
How many degrees of rotation does the CAMSHAFT make in a complete 4 stroke cycle
360
69
When referring to the total timing of an engine under load, what should a normal operating engine (working as designed with no faults) have at 3500+ RPM
35 degrees
70
What are the three types of stress testing?
Cold Testing
Heat Testing
Moisture Testing
71
What is the procedure for checking a waste spark coil's secondary winding?
Measure between both secondary output posts
72
What are the forms of trace pattern used when diagnosing a ignition system?
Firing Line
Intermediate Section
Dwell Section
Spark Line
73
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
74
A technician is testing a hall effect sensor. He inserts a steel feeler gauge between the hall layer and the magnet. When he does this the sensor reads battery voltage. When he removes the feeler gauge the sensor reads battery voltage. What is the likely fault?
The sensor is shorted to voltage
75
When diagnosing an ignition system fault that has not produced a DTC, what should be checked first?
Input signals
76
What would a leaner air/fuel mixture produce?
An Increase the electrical resistance inside the cylinder and increase the required firing voltage
77
What does the spark line represent?
The time the spark actually lasts
78
While checking a pickup coil with an ohmmeter, what would a higher then normal reading indicate?
High resistance
79
What can a hall effect cap sensor be checked with?
Voltmeter
80
An inspection of spark plugs reveals that they are overheated. What condition could cause this?
Fuel of too low on octane
81
When using a logic probe, what does a red light indicate?
More than 10 volts at the test point
82
Which type of distributor will use a shutter wheel in the distributor (one shutter per cylinder)
Hall Effect
83
Which distributor type has the most precise capabilities for reading engine position (up to 1 degree of camshaft rotation)
Optical
84
What may cause a vehicle to lose the cam/crank sync signal
Cam timing out one tooth
85
A Peizo sensor is used for what function on a modern automobile
To detect detonation events and retard the timing
86
A waste spark system will fire companion cylinder at the end of which strokes?
Compression and exhaust strokes
87
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, When the driver is grounding the circuit to charge the coil, the voltage is very low (near 0 V).
88
Which ignition system has the longest coil dwell time?
DIS coil on plug
89
A technician has removed and installed a distributor on a computer controlled ignition system. It needs to be enter "Base timing mode" to set the base timing.
What is the role of the computer when it is put into base timing mode?
The computer does not control the base ignition timing
90
On a DIS system, how is engine load calculated for ignition timing?
It monitors the Manifold absolute pressure sensor and the Throttle position sensor
91
When a DIS waste spark system detects a misfire, what does the computer do to try and repair the misfire?
It will increase dwell time to deliver a higher output from the secondary winding
92
What component is used on distributor systems to add additional timing under cruise conditions?
Vacuum advance
93
When setting base timing on an ignition system that uses computer controlled timing. How does a technician perform this task?
Set the base timing by adjusting the distributor with the engine off and at cylinder #1 at TDC compression stroke
94
When the PCM detect a voltage from the knock sensor it will?
Decrease the ignition timing
95
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?
The transistor is faulty
96
Modern vehicles require a crankshaft __________________ to run a misfire monitor?
Adaptive numerator
97
What condition requires more timing (additional advance) to obtain complete combustion?
A lean air fuel ratio
98
Mechanical advance weights on a distributor are stuck in the OUT position, what effect will this have on the vehicle?
Hard starting
Automotive Level 3
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