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.
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
computer PCM (Powertrain
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.
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 from
battery voltage. This electrical
signal is generated by the crankshaft position sensor (CKP), camshaft position sensor
(CAS). The PCM calculates spark timing by using the computer system.
DIS Distributorless Ignition 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. 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 PCM 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.
Distributor Cap and Rotor
The distributor cap and rotor are two essential pieces that distribute electrical
current to the spark plugs. The distributor cap connects to the spark plugs directly
using a spark plug wire. The number of plug wires connected depends on the amount
of spark plugs that are in the engine. For example, an eight cylinder engine will
have eight plug wires. The rotor is designed to spin inside of the distributor cap,
just missing the terminals inside the cap. A worn or damaged rotor can cause your
vehicle to run rough, or even stall completely. The rotor is rotating at the same
speed as the camshaft which also happens to be 1/2 the speed of the crankshaft.
Distributor Cap and Rotor (appearance may vary)
A problem occurs when the contacts inside the distributor cap can become dirty
and worn. It is best to replace the distributor cap and rotor every tune up to ensure
the contacts are clean to transmit power to each spark plug. The distributor cap
and rotor generally have few problems other than worn connections that results in
the cap needing to be replaced. There are numerous brands of distributor caps and
rotors that are available. It is your decision to select the appropriate brand based
on your individual wishes. However, when selecting the distributor cap and rotor
it is best to select an OE (original equipment) replacement for proper performance
and durability. If a misfiring problem has occurred and you cannot determine the
cause of it, it is advisable to inspect the distributor cap and rotor for corrosion.
Worn ignition components can cause the vehicle to misfire which leads to
wasted fuel, rough running
and stalling. Some early distributor ignition
systems featured a point set and condenser. A solid state system was later adopted.
