Diesel injectors are crucial components in common rail engines, contributing significantly to fuel efficiency and emissions reduction. However, they can be subject to failures that affect engine performance. Here is a comprehensive guide on how to check diesel injectors, focusing in particular on electrical checks.
Importance of Electrical Injector Control
When problems with starting or stopping the engine suddenly occur in a diesel vehicle, the cause can often be attributed to a malfunction of the injectors. In the absence of problems related to fuel pressure or defects in the control unit, it is crucial to examine the injectors, especially their electrical connections.
Preliminary Checks
Before proceeding with specific tests, it is essential to exclude other possible causes of malfunction, such as faulty sensors or EGR valves. Once you have verified that the diesel pressure and the ECU functions are normal, you can proceed with checking the injectors.
Checking Electrical Connections
An initial check is the electrical connections of the injectors. A short circuit in these components can cause all the injectors to fail, preventing the engine from starting. This check can reveal errors such as P0200 or P1213, indicating malfunctions in the injector circuit.
Injector Resistance Check
The internal resistance of the injector is a critical parameter, which varies depending on the type of injector (electromagnetic or piezoelectric) and can be influenced by temperature. Typical values are:
- Petrol: 13-16 Ω
- Diesel C/R electromagnetic: 0.5 – 1 Ω
- Diesel C/R piezoelectric: 180 – 200 kΩ
To check the resistance, use a multimeter set to ohms, disconnecting the injector connector and placing the probes on the two pins of the injector.
Isolating the Injector Wiring from Ground
This check is done to ensure that there is no continuity between the injector wires and ground, indicating proper insulation. If there is insulation, the multimeter will show infinite resistance. If, however, it registers low or zero resistance, this indicates a short to ground.
Procedure for Isolating the Injector Wiring from Ground
If a short to ground is suspected, it will be necessary to locate whether the problem is in the injector or the wiring harness. This is done by disconnecting the injector connector and measuring the resistance for both pins of the connector (wiring harness side), with the ECU connector disconnected.
Diesel injector diagnosis and testing are crucial to maintaining optimum engine performance. Through the electrical checks described, it is possible to identify and resolve injector problems, thus avoiding more serious engine damage. Remember that for such technical operations, it is always advisable to contact qualified professionals.
