Sidestick wrote:

Each injector is supplied with pressurised fuel from the fuel rail and delivers finely atomised fuel directly into the combustion chambers. Each injector is individually controlled by the ECM which operates each injector in the firing order and controls the injector opening period via PWM signals. Each injector receives a 12V supply from the ECM and, using programmed injection/timing maps and sensor signals, determines the precise pilot and main injector timing for each cylinder. If battery voltage falls to between 6 and 9V, fuel injector operation is restricted, affecting emissions, engine speed range and idle speed. In the event of a failure of a fuel injector, the following symptoms may be observed:
Engine misfire
Idle irregular
Reduced engine performance Reduced fuel economy
Difficult starting
Increased smoke emissions.
The ECM monitors the wires for each injector for short circuit and open circuit, each injector and the transient current within the ECM. If a defect is found, an error is registered in the ECM for the injector in question

geoffsnook wrote:

No a IID will not adjust it as i said it's done by the ecu i think there basically fly by wire

Sidestick wrote:

Suppose you need a tool like IID or similar to manage the idle rev