"N54 Engine: Diagnosis of Cold Start Rough Running with Misfire Faults. The customer may complain that during the cold start in the morning, the engine runs very roughly and the Service Engine Soon lamp is illuminated. Various misfire fault codes (e.g., 29CC, 29D2, 29D1, 29D0, 29C0, 29CF) may be stored in the DME control module. The engine rough running complaint can be reproduced on a cold start in the workshop. During the course of diagnosis, the spark plugs, removed from the misfiring cylinders after the problem was reproduced, are found to be soaked (""wet"") with fuel, while the injector tips are covered with a layer of carbon deposit. Possible cause: high-pressure injector failure (leakage or incorrect spraying pattern) due to internal wear or unfavorable stock of tolerances IMPORTANT: For comprehensive N54 drivability diagnostics, always refer to the ""N54 Engine Diagnostic Fault Tree"" file (the current version ""02_14_13"" is found as a PDF attachment to SI B12 55 06)."
