What the ECU checks
The Nexus monitors the current each injector output draws. If a circuit draws much less than it should, or much more, something is wrong in the wiring or the injector. It also keeps an eye on injector duty, which tells you when you've run out of injector. Each check can be turned on separately in NSP.
The settings
| Setting | What it catches | Triggers engine protection? |
|---|---|---|
| Enable Injector 90% Duty Cycle Exceeded DTCs | Any injector output going above 90% duty | No. It sets a code as a warning only |
| Enable Open Circuit DTCs | An output that's open circuit, or draws less current than expected: an unplugged connector, a broken wire, or a failed coil | Yes, at the severity you choose |
| Enable Short Circuit DTCs | An output that's shorted, or draws more current than expected: a pinched wire or a shorted coil | Yes, at the severity you choose |
| DTC Severity (one for open, one for short) | Which severity level the fault triggers | This sets the engine protection response |
| Minimum Voltage to perform short/open circuit checks | Stops the checks when battery voltage is too low to trust them, such as while cranking | Default 11.50 V |
How we set it up
- Turn on the 90% duty warning. It costs nothing. If you see it in a log, your injectors or fuel pressure are at their limit and the engine may be going lean at the top end.
- Turn on open and short circuit checks and pick a severity that fits the car. On a high-power engine, a dead injector means one very lean cylinder, so a protective response is worth having. On a mild street car, a warning may be enough.
- Leave the minimum voltage near the default unless you have a reason to change it. If you get false codes during cranking or with a weak battery, fix the charging or battery problem before lowering it.
If a code appears
Check the connector at the injector first, then the wire back to the ECU. Most open circuit codes turn out to be a connector that isn't fully latched. Look the code up in the DTC index for exactly which output it refers to.
Injector sizing and data live in the fuel system setup. The rest of the engine setup is under engine configuration.
