Engine Misfire at High Temperature (PD) (Solution)

Rough idle at high operating temperature; when the engine is started while warm, it runs with misfires for the first few seconds.

Cause:
The solenoid valve needle in the common rail injector occasionally jams at high fuel temperatures. The cause is a coaxial misalignment of the solenoid valve needle. When there is a low amount of fuel in the tank, the fuel temperature can reach approximately 90° Celsius. This reduces the clearance between the solenoid valve needle and the guide disc in the common rail injector, leading to the jamming of the solenoid valve needle.

Solution:
Read measurement data from channel 13, starting with a fuel temperature of 40° Celsius and increasing in steps of 10° Celsius up to 90° Celsius.

If a significant change in the idle injection quantity is detected for a cylinder, either positive or negative, the injector element for that cylinder needs to be replaced. A slight variation in the idle injection quantity for the remaining cylinders is acceptable, as the idle speed control system regulates itself based on the performance of the other cylinders.

After replacing the faulty injector nozzle element, the measurement sequence must be repeated to confirm the success of the repair.