The N55 engine, known for its performance and efficiency, sometimes suffers from a common issue: Valvetronic motor failure. This article explores the symptoms, causes, and solutions related to N55 Valvetronic Motor Replacement.
Understanding the N55 Valvetronic System
The Valvetronic system in the N55 engine utilizes an electric motor to precisely control valve lift, optimizing performance and fuel economy. This intricate system relies on accurate sensor readings to function correctly. A crucial component is the Valvetronic motor, responsible for adjusting the eccentric shaft that dictates valve lift.
Symptoms of a Failing Valvetronic Motor
One of the most common indicators of a failing Valvetronic motor is a clicking noise upon starting the car, especially prevalent in cold weather. This clicking often disappears as the engine warms up. This symptom suggests a malfunctioning Hall sensor within the Valvetronic motor. Hall sensors detect the motor’s position and relay this information to the DME (Digital Motor Electronics). When a Hall sensor fails, it disrupts this communication, leading to inaccurate positioning and the characteristic clicking noise as the motor hits its physical limits.
Other potential symptoms include:
- Increased Fuel Consumption: A malfunctioning Valvetronic system can disrupt optimal valve timing, leading to reduced fuel efficiency.
- Rough Idle: Inconsistent valve lift can cause a rough or unstable idle.
- Reduced Performance: The engine may experience a loss of power or responsiveness due to improper valve control.
- Fault Codes: Diagnostic trouble codes related to the Valvetronic system may be stored in the DME. Common codes include 135808 (Valvetronic Servomotor) and 135A08 (Valvetronic Servomotor Position Sensor).
Why Valvetronic Motors Fail
The clicking noise associated with cold starts points to the sensitivity of the Hall sensors to temperature fluctuations. The cold can affect the magnetic field readings, hindering the sensor’s ability to accurately determine the motor’s position. This leads to the DME continuously powering the motor, causing it to hit its physical end stops and produce the clicking sound.
Furthermore, the Valvetronic motor demands a significant current (around 40 amps) to operate. A weak or aging battery may struggle to provide the necessary power, potentially contributing to motor failure. The DME activates the Valvetronic system upon opening the car doors, placing an immediate demand on the battery.
The Solution: N55 Valvetronic Motor Replacement
In most cases, a failing Valvetronic motor requires replacement. While the run-in procedure is recommended after replacing the actuator, it doesn’t address underlying issues with a faulty motor. Replacing the motor ensures accurate valve control, restoring performance and fuel efficiency. Given the prevalence of this issue, it’s suspected that certain Valvetronic motors may have been manufactured with faulty components.
Conclusion
A malfunctioning Valvetronic motor can significantly impact the performance and efficiency of the N55 engine. Recognizing the symptoms, such as the telltale cold start clicking, is crucial for early diagnosis. While a weak battery can exacerbate the issue, the primary solution typically involves replacing the Valvetronic motor itself. This replacement restores proper valve control, ensuring optimal engine operation.
