Fuel Injection Pattern and Injection Timing

Fuel injectors can be pulsed in one of four patterns depending on application. These injection patterns are:

• Simultaneous

• Two groups of two injectors each (four cylinder engines)

• Three groups of two injectors each (six cylinder engines)

• Independent (sequential)

The following chart represents fuel injection grouping and timing patterns.

Because injection timing is based on engine rpm, the eCu must receive an rpm signal to operate the injector driver circuits. With Conventional EFI, this signal comes directly from the coil and is identified as IG. With TCCS, the rpm and crankshaft position identification signals come from the Ne and G1 sensors located in the distributor. If these signals are lost, the ECU will not pulse the injectors.

Toyota Fuel Injection System
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