Step by step guide on how an automotive engine ignition system works. This article
pertains to all internal combustion engines.
must utilize an ignition system which is used to ignite the fuel air
mixture inside the combustion chamber.
Engine Ignition System Action Cut-Away - An ignition system starts by referencing
the crankshaft while in motion, this rotation produces electrical impulses which
are sent to the car's computer for translation.
Crankshaft Angle Sensor
- A sensor is used at the rear of the crankshaft
also to measure crankshaft flex while making further adjustments.
Rear Crankshaft Positioning Wheel - Camshaft angle sensors are used to give
feedback data to the computer to also help with ignition timing.
Camshaft Angle Sensors - This feedback data is transferred the
computer via the wiring harness.
Wiring Harness - Once this data is received by the
, an ignition coil trigger signal is generated by the coil drivers inside
the computer. This signal timing is a product of manufacturer software loaded onto
the computer which makes adjustments using feedback data from various sensors.
Computer - After the signal is generated its
transferred to the ignition coil via the wring harness. Once the signal has been
receive by the coil, a magnetic field collapses increasing from 12 volts to about
25,000 volts which is needed to bridge to gap of the spark plug.
Ignition Coils - An ignition coil is mounted over the spark
plug directly. Some ignition designs are fitted with ignition wires which connects
to the spark plugs.
Ignition Coil Removed - The ultimate goal of the ignition system
is to fire the spark plug at the right time to maximize power and efficiency of
the engines cylinders.
Spark Plug - Once the piston is near the top of its
compression stroke the coil is triggered, releasing the voltage charge across the
spark plug gap igniting the fuel air mixture inside the engine's cylinders. Some
engine's utilize two spark plugs per cylinder to further enhance efficiency.
Spark Plug Ignition Helpful Information
An ignition system is designed to ignite a fuel mixture inside the engine's combustion
chamber at an 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 a low voltage trigger system i.e.
crankshaft position sensor
(CKP), camshaft position sensor (CAS) to trigger a high voltage spark. 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 secondary side of the ignition coil.
This efficient system does not need adjustments or calibrations of any kind.
The system is designed to automatically make timing adjustments via the computer
program, while accounting for all variations of engine demand. If a misfiring problem
has occurred, check the ignition system by
reading trouble codes
, and testing the
. Worn ignition components can cause the vehicle to misfire which could
is needed. When an
its typically caused by the ignition system. Proper maintenance
can help ensure the ignition system operates at peak performance.
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 (high voltage) electrical
system (spark plug.)
Inside an ignition coil are small wires wrapped around two iron cores. The secondary
core has far more turns of wire than the primary coil, this offset is what causes
electrical voltage to dramatically increase when the lower voltage field is broken.
If any component of the ignition system is not functioning properly, it can cause
an entire ignition system to shut down.
In older systems a distributor, points, condenser and a vacuum advance unit performed
the job of the ignition system. A distributor cap, rotor and wires were essential
pieces that distributed electrical voltage to the spark plugs which were fitted
to the engine distributor. The rotor is designed to spin inside of the distributor
cap while mounted to the distributor housing which is connected to the engine camshaft
using a gear. The distributor rotates at the same speed as the camshaft which is
half the speed of the crankshaft (engine speed.) These systems need to have the
timing adjustment set
Historic Ignition System Operation
Article first published