Ignition System

1
Ignition System

• Provides a method of turning a spark ignition
  engine on off.

• Operates on various supply voltages (Battery
  Alternator)

• Produces high voltage arcs at the spark plug
  electrode.

• Distributes spark to each plug in correct
  sequence.

• Times the spark so that it occurs as the piston
  nears the TDC on the
• compression stroke.

• Varies the ignition timing as engine speed, load
  and other conditions
• change.

2
Ignition Parts
BATTERY provides power for system.
IGNITION SWITCH allows driver to turn ignition on
and off.
IGNITION COIL changes battery voltage to 30,000V
during normal operation and has a potential to
produce up to 60,000V.
SWITCHING DEVICE mechanical or electronic switch
that operates Ignition coil(Pick-up coil, Crank
sensor, Cam sensor).
SPARK PLUG uses high voltage from ignition coil
to produce an arc in the combustion chamber.
IGNITION SYSTEM WIRES connect components.
3
Ignition Circuits
PRIMARY CIRCUIT

• Includes all the components
• working on low voltage
• (Battery, Alternator).

SECONDARY CIRCUIT

• Consists of wires and points
• between coil out-put and the
• spark plug ground.

4
Ignition Coil
Primary Windings are made up of several hundred
turns of heavy wire wrapped around or near the
secondary windings.
Secondary Windings consist of several
thousand turns of very fine wire, located inside
or near the secondary windings.
5
Distributor

• Actuates the on/off cycle of current flow through
  the ignition coil
• primary windings.

• It distributes the coils high voltage to the
  plugs wires.

6
Distributor

• It causes the spark to occur at each plug earlier
  in the compression
• stroke as engine speed increases, and vice versa.

• Changes spark timing.

• Some distributor shafts operate the oil pump.

7
Point Ignition System
PARTS Distributor Cam, Breaker Points, and
Condenser.
8
Point Ignition System
Points are wired in Primary Circuit When the
points are closed, a magnetic field builds in
the coil. When the points open, the field
collapses and voltage is sent to one of the
spark plug.
9
Electronic Ignition System

• Trigger wheel passes by the pick-up coil.

• of cylinders of teeth.

10
Ignition Control Module

• An electronic switch that turns the ignition coil
  primary current on/off

LOCATION

• Engine compartment

• On the side of distributor

• Inside the distributor

• Under vehicle dash

11
Distributor Cap

• Insulated plastic cap

• Transfers voltage from coil (wire) to Rotor.

12
Distributor Rotor

• Transfers voltage from the distributor cap
• center terminal(coil) to distributor cap
• outer terminals(spark plugs).

• Provides spark in the correct Firing Order.

• Sometimes the firing order can be found
• on the intake manifold.

13
Ignition Timing
How early or late the spark plug fires in
relation to the position of the engine piston.
 
Ignition timing must change with the changes in
engine speed, load, and temperature.
14
Ignition Timing
Timing Advance occurs when the plug fires sooner
on compression stroke (High engine speed)
Timing Retard occurs when plug fires later on
compression stroke (Lower engine speed)
BASE TIMING Timing without vacuum or computer
control.
15
Methods of controlling Timing
Distributor Centrifugal Advance

• Controlled by engine speed.

• Consists of two weights and two springs.

• At high speeds the weights fly out(held by the
  springs), rotating the
• cam, hence advancing the timing.

16
Methods of controlling Timing
Vacuum Advance

• Controlled by engine intake manifold vacuum and
  engine load.

• The vacuum diaphragm rotates the pickup coil
  against the direction
• of distributor shaft rotation.

17
Methods of controlling Timing
Electronic Advance Sensors input influences the
ignition timing.

• Crank shaft Position Sensor (RPM)

• Cam Position Sensor (tells which
• cylinder is on compression stroke)

• Manifold Absolute Pressure (MAP)
• (engine vacuum and load)

18
Methods of controlling Timing
Electronic Advance Sensors input influences the
ignition timing.

• Intake Air Temperature Sensor

• Knock Sensor (Retards timing when pinging
• or knocking is sensed)

• Throttle Position Sensor(TPS)

• Engine coolant Temperature

19
Ignition System
Distributor VS Distributor Less Ignition System
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DIS Ignition System

• Less moving parts.

• No Distributor.

• Uses multiple ignition coils.

• Camshaft position sensor is installed in place of
  ignition distributor.

• ECM fires two coils at the same time.

21
Direct Ignition System
Mounted directly on the plugs (Quad-4 )
No Sparkplug wires.
22
Ignition System