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Core EFIV4 Manual

04 · Wiring

Injectors · 4 / 6 / 8 cyl

Four primary high-Z injector drivers. Cylinder count is assignable: 4-cyl sequential on those four, 6-cyl 3-channel matched through an external driver on K1 / J3 / J4, 8-cyl two-channel batch through J4 / J3.

The four primary outputs

C4, C3, B4, B3 are Injector 1–4. The ECU switches ground. Injector 12 V comes from main-relay 87. Cylinder order is a TunerStudio table.

4-cylinder — sequential

One injector per primary output. Sequential with a cam on F4, or batch/semi-sequential on crank only.

6-cylinder — 3-channel matched

Three matched batch channels through an external injector driver. Trigger that box from K1 (Ignition 4), J3 (GPO 5) and J4 (GPO 6). Two injectors per channel. Primary Inj 1–4 stay unused for fuel. Confirm 5 V vs 12 V jumper on GPO 5 / 6, and that Ign 4 is set as a fuel output — not a coil — in TunerStudio.

8-cylinder — two-channel batch

Two injector channels: J4 (GP Out 6, Injectors A) and J3 (GP Out 5, Injectors B) into an external driver. Four injectors per channel. Primary Inj 1–4 stay unused for fuel. Confirm 5 V vs 12 V jumper on GPO 5 / 6.