System Description

Ignition System Schematic:

DESCRIPTION
The Electronic Ignition System (EI) consists of a crankshaft mounted Crankshaft Position (CKP) Sensor, a Camshaft Position (CMP) Sensor, Ignition Control Module (ICM), the Powertrain Control Module (PCM), and an Ignition Coil Pack.

The CKP Sensor is a Hall effect device that responds to a rotating metallic vane mounted on the crankshaft damper assembly. The signal generated by this sensor is called the CKP signal. The CKP signal provides base timing and RPM information to the ICM and PCM.

The CMP Sensor is a single Hall effect magnetic switch, which is activated by a single vane driven by the camshaft. This sensor provides camshaft position information to the ICM for use in determining coil firing sequencing.

The EI eliminates the distributor by using multiple ignition coils. Three coils are mounted together in a coil pack. The coil pack has three tach wires, one for each coil.

OPERATION
During normal operation, the CKP signal is sent to the PCM module from the crankshaft timing sensor and provides base timing and RPM information. The CMP signal provides the ignition control module with the information required to synchronize the ignition coils so that they are fired in the proper sequence.

If there is a fault and the ICM does not receive the input signal from the PCM it will automatically turn the ignition coils on and off using the CKP signal. This will result in fixed spark timing and fixed dwell.

Each coil fires two spark plugs at the same time. The plugs are paired so one fires during the compression cycle while the other fires during the exhaust stroke. The next time the coil is fired, the plug that was on the exhaust stroke will now be on the compression stroke and visa versa. The spark that is used on the exhaust stroke is wasted but little of the coil energy is lost.