Why disable the injectors?
During setup you'll crank the engine several times: to build oil pressure, check the trigger signals and confirm timing. If the injectors are live, each crank sprays fuel into cylinders that aren't firing yet. That raw fuel builds up, washes oil off the cylinder walls, dilutes the oil in the sump, and can hydraulically lock a cylinder in bad cases. Disabling the injectors removes all of that risk.
How to do it
- Pull the injector fuse if your harness has one feeding the injector supply. This is the quickest method.
- Unplug the injectors at their connectors if there's no separate fuse.
- Either way, it's a good time to disconnect the fuel pump too if you don't need fuel pressure for your checks.
Before you turn them back on
Only reconnect the injectors once you've confirmed the ECU is powered and communicating, the sensors read correctly, the engine has good oil pressure (see priming the oil system), and the trigger is reading steadily. Then follow enabling injectors.
