Adjusting Throttle (Dashpot) Unit

When engine speed is below 2000 RPM and vacuum unit does not release throttle linkage, proceed as follows:

1. Disconnect vacuum hose from vacuum unit, make sure vacuum exists in hose. If vacuum exists, vacuum unit is defective and must be replaced.
2. If vacuum does not exist in hose, disconnect lead from control valve and check continuity using a suitable test lamp.
   NOTE: When testing, engine speed should remain above 2000 RPM.
3. When checking continuity, if test lamp lights up, control valve is faulty and should be replaced. If test lamp does not light up, RPM switch is faulty and should be replaced.
   Fig 1: Throttle Vacuum (Dashpot) Unit

   Courtesy of BMW OF NORTH AMERICA, INC.