Ignition System: Description and Operation

Ignition System Diagram:

DESCRIPTION
The Miata uses a distributorless ignition system similar to that found in the RX-7. Ignition control is achieved without a distributor, pick-up coil, reluctor (signal rotor) or ignition module. Main components of this system are an optical pick-up type crank angle sensor, two ignition coils, an igniter, and the ECU.

OPERATION
The crank angle sensor, mounted on rear of the cylinder head, detects crankshaft angle and provides a reference signal to the ECU. This information, together with input from various other sensors, permits the ECU to monitor engine operating conditions and compute optimum ignition timing at any given moment. Each coil fires two spark plugs simultaneously when the ECU operates the igniter to regulate current flow interruption in the coil primary windings.

NOTE: If a timing light is used to check for spark, some lights do not illuminate at No. 2 and No. 4 cylinders, even if the ignition system is okay.