The following procedure shows how to verify in under 15 minutes that the injectors are in good condition electrically, whether the ECU is supplying power to the injectors and that the injector wiring loom is in good order, without substituting any spare parts.
Professionaltype oscilloscopes can be expensive (£500+), but we have seen them priced as low as £99. This one connects to a conventional laptop. C4
With the engine running, the live reading data from injector number 1 shows a regular pattern of identical waves, indicating that it is healthy electronically. C5
Fitted with basic solenoid injectors, the connectors can be back-probed in order that the voltage can be read over time with an oscilloscope. C3
Aside from a smell of petrol, the excessive carbon monoxide, measured by an emissions probe, indicates that unburned fuel is present. C2
The misfire on this 2007 Ford Focus 1.8 has not triggered an engine warning light, but the fault lies either in the ignition or fuel systems. C1