Allston Auto Repair

A BMW that hesitates when you pull away can leave you with several unfamiliar terms on a diagnostic report. VANOS appears in one fault description, Valvetronic in another. Both involve the valves and can affect how the engine runs, so it's easy to assume they're just two names for the same repair. They aren't. Before authorizing a solenoid, motor, or cylinder-head repair, you should know which adjustment is failing and what testing supports that conclusion. The driving symptoms overlap enough that the dashboard message alone to separate them.    VANOS Changes Timing; Valvetronic Changes Lift VANOS adjusts when the valves open and close by changing camshaft timing. On many BMW engines, oil pressure moves the camshaft adjusters under electronic control. This lets the engine use different valve timing at idle, during acceleration, and at higher speeds. Valvetronic changes how far the intake valves open. An electric motor and eccentric-shaft ... read more