Pickups

To monitor engine rpm, the TCCS system uses the signal from a magnetic pickup called the Ne pickup . The Ne pickup is very similar to the magnetic pickup coil used with Conventional EFI . It has either four or 24 reluctor teeth, depending on engine application . Engines equipped with the ESA system (and the 4A - GE engine with VAST) use a second pickup in the distributor called the G sensor . The G sensor supplies the ECU with crankshaft position information which is used as a reference for ignition and fuel injector timing . Some engines use two G sensors, identified as G1 and G2 .

ESA Ignition System Operation

In the example above, when the engine is cranked, an alternating current signal is generated by a 24 - tooth Ne pickup and a four - tooth G pickup .

These signals are sent to the ECU where they are conditioned and relayed to the microprocessor . The microprocessor drives a trigger circuit , referred to as IGt (TR1) . The IGt signal is sent to the igniter to switch the primary circuit power transistor on and off . While cranking, IGt fixes spark timing at a predetermined value . When the engine is running, timing is calculated based on signals from engine speed, load, temperature, throttle position, and detonation sensors . The IGt signal is advanced or retarded depending on the final calculated timing . ESA calculated timing is considered the ideal ignition time for a given set of engine conditions . If the ECU fails to see an Ne or G signal while it is cranking, it will not produce an IGt signal, thus preventing igniter operation .

EFI #4 - TCCS IGNITION SYSTEM Toyota