The electronic ignition (EI) system produces and controls the high energy secondary spark. This spark ignites the compressed air/fuel mixture at precisely the correct time, providing optimal performance, fuel economy, and control of exhaust emissions. The powertrain control module (PCM) primarily collects information from the crankshaft position (CKP) and camshaft position (CMP) sensors to control the sequence, dwell, and timing of the spark.

The crankshaft position (CKP) sensor is a permanent magnet generator known as a variable reluctance sensor. The CKP sensor produces an AC voltage of varying amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC output depends on the CKP and the battery voltage. The CKP sensor works in conjunction with a 58-tooth reluctor wheel attached to the crankshaft. As each reluctor wheel tooth rotates past the CKP sensor, the resulting change in the magnetic field creates an ON/OFF pulse 58 times per crankshaft revolution. The powertrain control module (PCM) processes the pulses to create a pattern that enables the PCM to determine the CKP. The PCM can synchronize the ignition timing, the fuel injector timing, and the spark knock control based on the CKP sensor and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and for tachometer display. The PCM learns the variations between all 58 teeth under different speed and load conditions to correctly detect misfires. The CKP sensor circuits consist of a signal circuit and a low reference circuit. The 2 wires are twisted together to prevent electromagnetic interference (EMI) on the CKP sensor circuits.

The crankshaft reluctor wheel is part of the crankshaft. The reluctor wheel consists of 58 teeth and a reference gap. Each tooth on the reluctor wheel is spaced 6 degrees apart with a 12-degree space for the reference gap. The pulse from the reference gap is known as the sync pulse. The sync pulse is used to synchronize the coil firing sequence with the crankshaft position (CKP), while the other teeth provide cylinder location during a revolution.

This system consists of 2 different camshaft position (CMP) sensors, the exhaust CMP sensor and the intake CMP sensor. The exhaust CMP sensor is triggered by a notched reluctor wheel built into the exhaust CMP actuator. The CMP sensor provides 5 signal pulses every camshaft revolution. Each notch, or feature of the reluctor wheel, is of a different size for individual cylinder identification. This means the CMP and crankshaft position (CKP) signals are pulse width encoded to enable the powertrain control module (PCM) to constantly monitor their relationship. This relationship is used to determine camshaft actuator position and control its phasing at the correct value. The PCM also uses this signal to identify the compression stroke of each cylinder, and for sequential fuel injection. The intake CMP sensor is triggered by a 1X reluctor wheel built into the intake camshaft sprocket. The CMP sensor provides one signal pulse every camshaft revolution. The PCM monitors this signal and the CKP signal for startability. Both of the CMP sensors are connected to the PCM by a 12-volt circuit, a low reference circuit, and a signal circuit. The 12-volt reference circuit is shared by the 2 sensors, while the low reference circuit and the signal circuit is independent.

Each ignition coil/module has the following circuits:

The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the IC circuit of each ignition coil/module to enable a spark event.

The spark plugs are connected to each coil by a short boot. The boot contains a spring that conducts the spark energy from the coil to the spark plug. The spark plug electrode is tipped with platinum for long wear and higher efficiency.

The powertrain control module (PCM) controls all ignition system functions, and constantly corrects the spark timing. The PCM monitors information from various sensor inputs that include the following:

During normal operation, the powertrain control module (PCM) controls all ignition functions. If either the crankshaft position (CKP) or the camshaft position (CMP) sensor signal is lost, the engine will continue to run because the PCM will default to a limp-home mode using the remaining sensor input. Each coil is internally protected against damage from excessive voltage. If one or more coils were to fail in this manner, a misfiring condition would result. DTCs are available to accurately diagnose the ignition system with a scan tool.