General Description

PURPOSE
The Ignition System is designed to ignite the compressed air/fuel mixture in an internal combustion engine by a high voltage spark from an ignition coil. The ignition system also provides engine timing information to the Powertrain Control Module (PCM) for proper vehicle operation and misfire detection.

COMPONENTS
The Integrated Electronic Ignition (EI) system consists of a Crankshaft Position (CKP) Sensor, coil pack, connecting wiring, and PCM.

OPERATION
- The CKP Sensor is used to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted to the crankshaft.

- The PCM uses the CKP signal to calculate a spark target and then fires the coil pack to that target.

- The coil pack receives its signal from the PCM to fire at a calculated spark target. Each coil within the pack fires two spark plugs at the same time. The plugs are paired so that as one fires during the compression stroke the other fires during the exhaust stroke. The next time the coil is fired the situation is reversed.

- The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, battery power applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, the power is interrupted and the primary field collapses inducing the high voltage in the secondary coil windings and the spark plug is fired. A kickback voltage spike occurs when the primary field collapses. The PCM uses this voltage spike to generate an Ignition Diagnostic Monitor (IDM) signal. IDM communicates information by pulsewidth modulation in the PCM.

- The PCM processes the CKP signal and uses it to drive the tachometer as the Clean Tach Out (CTO) signal.

NOTE: Electronic Ignition engine timing is entirely controlled by the PCM. Electronic Ignition engine timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.