The ignition system in your car ignites the fuel inside the
engine's combustion chamber at the optimal time in the
piston stroke to produce the most power while emitting the least amount of
emissions as possible. There are many configurations of ignition systems but all
operate on the same principle, create a low energy field and collapse it
onto a high energy coil and that transfers the electrical energy into the
secondary ignition system, i.e. coil wire, distributor cap and rotor (if
equipped) plug wires and finally the spark plug.
Typical Ignition System in Operation
This system is triggered by the primary
ignition system, this system varies depending on manufacturer but all operate on
the same principle, use some kind of low voltage trigger system i.e. crankshaft
position sensor (CKP), camshaft position sensor (CAS). This low voltage system
(1.5 to 3.0 volts) is amplified to 12 volts by using an ignition module
(amplifier) and then transferred to the primary side of the ignition coil. The
ECM (engine
control module) controls the engine ignition timing by advancing and
retarding the primary trigger signal. In old cars a points, condenser and a
vacuum advance unit performed this job.
Ignition Coil Cut-away
This ignition coil is a pulse-type it consists, in part, of two coils of
wire. These wires are wrapped around two iron cores. Because this is a step-up
transformer, the secondary coil has far more turns of wire than the primary
coil. The secondary coil has several thousand turns of thin wire, while the
primary coil has just a few hundred raps. This allows 40,000 volts or more of
voltage to be generated by a car battery.
This electrical signal is generated by the crankshaft position sensor (CKP),
camshaft position sensor (CAS). The
ECM
calculates spark timing by using the computer system.
Some ignition systems have a coil for each
spark plug.
This is called Direct Ignition (DI) system; there are no plug wires in this system
just individually controlled ignition coils. The amount of coils or spark plugs
depends on the number of cylinders the engine is designed with.
Coil Over Spark Plug Style
The initial power supplied to the ignition system is generated from the battery.
All vehicles use an
alternator
to recharge the
battery
during normal operation. A low battery can cause an engine not to start even
if the engine is cranking over slowly. This is because the vehicle voltage has dropped
below 12 volts. If any component of the ignition system is not functioning properly,
it can cause an entire ignition system failure. Proper maintenance such as a
tune
up can help ensure that the vehicle's ignition system operates at peak performance.
Spark Plug in Operation
When an engine misfires under power it is typically caused by the ignition system.
To troubleshoot the cause of the ignition system failure
scan the ECM
for
trouble codes and repair as needed. Maintenance to the ignition system includes
changing
the spark plugs and distributor cap and
spark
plug wires if equipped. Changing the spark plugs and wires usually is a simple
task that most people can perform themselves.
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