Valve adjustment on the S54 engine, found in the E46 M3, is a critical aspect of maintaining optimal engine performance and longevity. The S54 uses a dual VANOS system (BMW’s variable valve timing) and requires periodic valve clearance checks and adjustments due to the naturally occurring wear on the valve train components, particularly as the engine accumulates mileage. Over time, the valve clearances can change, which may lead to improper valve timing, decreased engine efficiency, rough idling, poor throttle response, and even a loss of power. In more severe cases, improper valve clearance can cause excessive wear on the camshaft, lifters, or valves themselves, potentially leading to more expensive repairs or engine damage. Regular valve adjustments help ensure that the engine runs smoothly, with optimal compression and combustion, which translates to improved power output, fuel efficiency, and overall reliability. While the S54 is known for its high-revving nature, maintaining proper valve clearance allows the engine to continue operating at its best, ensuring a smooth and responsive driving experience for years to come. As the S54’s valve adjustment interval typically falls between 60,000 to 100,000 miles, staying on top of this maintenance task is essential for preserving the health of the engine and avoiding costly repairs down the road.