The BMW N55 engine, while renowned for its performance, is known to have a few common issues. Understanding whether these problems can be identified using an OBD scan tool is crucial for BMW owners and prospective buyers alike. Let’s delve into some typical N55 engine problems and explore how a scan tool, specifically like the Autel MaxiDiag MD805, can assist in diagnosis.
One noted issue is high oil consumption in the N55. While a scan tool might not directly pinpoint a faulty crankcase vent valve (PCV), it can provide valuable data. Monitoring live data parameters such as air intake values and fuel trims could indirectly suggest a PCV issue affecting the engine’s vacuum and combustion.
Misfires are another common concern, often linked to carbonized hydraulic lifters. A scan tool excels at detecting misfires. It will register fault codes indicating misfiring cylinders, providing a clear starting point for investigation. While the scan tool won’t confirm carbonized lifters directly, the misfire codes are a critical first step in diagnosing this problem. Using a scan tool to read live data on engine smoothness and cylinder contribution can further help pinpoint misfiring cylinders.
Engine vibration, potentially stemming from faulty fuel injectors, is also reported. While a scan tool can’t physically test injectors, it can be instrumental in identifying injector-related problems. By reading fault codes, you may find codes related to injector circuit malfunctions or fuel trim imbalances. Furthermore, many scan tools, including the Autel MD805, offer live data streaming for fuel pressure and injector pulse width. Deviations from expected values can indicate injector issues.
The High Pressure Fuel Pump (HPFP) issue, familiar from previous BMW engines, can also affect the N55. Fortunately, an OBD scan tool is highly relevant here. The tool can read fuel pressure data from the DME (Digital Motor Electronics) module. Monitoring actual versus desired fuel pressure is crucial for HPFP diagnosis. A scan tool can also log fault codes related to fuel pressure deviations, indicating potential HPFP problems. Tools like the Autel MaxiDiag MD805, with its BMW-specific diagnostic capabilities, are well-suited for this task.
The Autel MaxiDiag MD805, as you’ve noted, can access modules like DME, DDE, EGS, and EKPS. This access is vital for reading fault codes and live data related to engine performance, fuel delivery, and transmission – all crucial for diagnosing N55 engine issues. While knowing the “correct” values requires BMW-specific technical documentation or comparison to a known good vehicle, observing deviations, inconsistencies, and fault codes is a significant step in N55 engine problem diagnosis using a scan tool.
In conclusion, while a scan tool might not solve every N55 engine problem directly, it’s an indispensable diagnostic tool. It can detect misfires, monitor fuel pressure for HPFP issues, and provide valuable data for investigating oil consumption and injector problems. For a prospective BMW owner, using a scan tool like the Autel MD805 is a smart move for pre-purchase inspections and ongoing maintenance.
