In 1986-90, Acura used the Programmed Ignition (PGM-IG) system in both the Integra and Legend. This ignition system is basically comprised of a distributor, an igniter, a control box, a high energy coil and related ignition wires. This ignition system is used in the 1986-93 Integra, 1986-1990 Legend and 1992-93 Vigor.
The distributor contains a reluctor mounted on a rotor shaft and a magnet mounted on a base plate. The pick-up coil is located around the rotor shaft but does not rotate with the shaft. The programmed ignition employed on these vehicles, provides optimum control of ignition timing by determining the optimum timing using a microcomputer in response to engine speed and vacuum pressure in the intake manifold, which are transmitted by signals from CRANK/CYL sensor, TDC sensor, throttle angle sensor, coolant temperature sensor and MAP sensor. This system, not dependent on a governor or vacuum diaphragm, is capable of setting lead angles with complicated characteristics which cannot be provided by conventional governors or diaphragms.
On the Integra, the igniter, and ignition coil are apart of the distributor assembly. The Legend, the igniter and ignition coil are separate of the distributor and are located near the control box. The igniter contains 3 resistors, 3 diodes and 2 transistors. The transistors act as switches which are activated at a precise voltage.
When the ignition is switched ON , the switching of the transistors in the igniter ensures that no current can flow in the ignition coil primary windings. When the engine is cranked, the reluctor moves through the magnetic field created by the stator and, when the reluctor teeth are aligned with the stator projections, a small AC voltage is created. The igniter amplifies this voltage and uses it to switch the transistors so that an earth path is provided to the primary circuit.
As the reluctor teeth move out of alignment with the stator projections, an abrupt change occurs in the AC voltage. The transistors are switched again and the primary circuit earth path is broken. This induces a high voltage in the ignition coil secondary winding.
A time control circuit in the igniter controls the charging time for the ignition coil according to engine speed, this reduces consumption at low engine speeds and prevents secondary voltage drop at high engine speeds.
The 1991-93 Legends are equipped with a distributorless ignition system. This system is still considered as Programmed Ignition (PGM-IG) system. The basic difference is that the distributorless system incorporates 1 ignition coil per cylinder as opposed to the distributor type system, which uses 1 ignition coil for the entire system.
System operation is accomplished when the ignition switch is in the RUN or START position. Battery current is applied through each of the ignition coils to the igniter. The igniter acts as a switch to control current through the primary windings of the ignition coils. The igniter is controlled by the PGM-FI electronic unit. When current to the ignition coil is stopped, a high voltage current flows to the spark plug. The ignition system is controlled by inputs to the PGM-FI electronic control unit. The inputs include; detonation, engine RPM, accelerator position, coolant temperature, ignition timing adjustment, manifold pressure, crankshaft position and exhaust oxygen content. Traction control and the automatic transmission also affect the ignition system.