Table of contents: Models produced in 1993 and 1994. ↓ Models since 1995. ↓
The ignition system serves to ignite the air-fuel mixture supplied to the engine combustion chambers at the right time. This task is performed by generating a high-voltage electric arc between the electrodes of the spark plugs screwed into each of the cylinders.
Models produced in 1993 and 1994.
The 1993 and 1994 models are equipped with a SOHC engine equipped with an electronic ignition system consisting of a distributor, a camshaft position sensor located in it, a power transistor, an ignition coil, a resistive-capacitive assembly and connecting wiring for the high-voltage and low-voltage circuits.
The camshaft position sensor sends reference signals to the on-board processor, which performs overall control of the ignition system. Based on the information received from the sensor, the PCM determines such critical engine parameters as its rotation speed and the position of the pistons in the cylinders and calculates the required moment and duration of operation of each of the fuel injectors. The camshaft position sensor consists of a rotor plate and a set of light-emitting diodes and photodiodes. The sensor generates a sinusoidal signal. Based on the analysis of the characteristics of this signal, the PCM generates commands to control the operation of the ignition system. The power transistor serves to amplify the ignition signal generated by the processor and instantly ground the primary circuit of the ignition coil, the secondary winding of which at this moment generates a high-voltage signal sent via special large-section wires through the distributor to the spark plugs.
The PCM receives multiple signals from various sensors and, based on the analysis of the incoming information, controls such parameters as the distribution and ignition timing via the power transistor and ignition coil (for more details, see Chapter Engine management systems).
Based on signals from the knock sensor, the RCM also monitors the efficiency of ignition of the air-fuel mixture, adjusting the ignition advance angle as necessary. Using the knock sensor allows the system to maintain the ignition advance angle at the maximum level, thereby providing optimal conditions for the operation of the power unit and allowing the greatest efficiency of the engine output with minimum fuel consumption.
High-voltage spark plug wires use a carbon conductor enclosed in a rubber insulating jacket and an outer silicone protective tube. Wires of this design are capable of withstanding high temperatures, while providing reliable insulation of the conductor through which the high-voltage current passes. Silicone tips ensure a tight fit of the high-voltage wire terminals on the spark plug tails. Before disconnecting the wire from the spark plug, the tip should be turned half a turn (for more details, see Chapter Settings and ongoing maintenance).
Models since 1995.
Beginning in 1995, Nissan Maxima vehicles began to be equipped with a direct ignition system that operates without a distributor. The system consists of six individual coils connected directly to the corresponding spark plugs. The PCM determines the ignition order based on signals received from the camshaft and crankshaft position sensors. In addition, the control module constantly receives signals from a number of other information sensors that continuously monitor engine operating parameters, and based on the analysis of incoming data, it produces optimal ignition timing settings.
The system also includes a knock sensor, which allows the PCM to maintain the optimum ignition timing.