The DISA valve is a common failure on the M54 BMW engines and is caused by the poor materials used in the manufacturing process in a couple of the key valve components. The three parts of the DISA are the flat plastic flapper valve, the bell crank lever that rotates the flapper, and the vacuum pot, all made of glass reinforced nylon. This construction of glass and nylon is what primarily creates failure points. The symptoms of a worn DISA valve include rough idle, lean engine codes and lack of low to mid rpm power.
We upgrade the DISA by replacing the plastic flapper valve and bell crank with machined aluminum and titanium parts which will last the life of the engine.
Return your old DISA with the supplied prepaid shipping label for a $50 core refund.