Sluggish Running Mini Cooper S, DTC P1688 Tech Tips
Vehicle: 2006 Mini Cooper S, L4-1.6L SC, Automatic Transmission/Transaxle
Problem: Vehicle had DTC P1688 (Electronic throttle control monitor level 2/3; mass air flow calculation) and low power. We found that an intake duct clamp was loose so we cleaned the throttle body and refitted the boot and tightened the clamp – no change. One of the techs found a TSB addressing the P1688 DTC, which said not to replace the DME control module without further testing of the supercharger bypass valve. The valve was good, but the TSB prompted further diagnosis.
Details: We noticed that the harmonic balancer was wobbling more than it should so we drew an alignment mark across the rubber ring so there were marks on the inner and outer ring. Started the engine and the alignment marks moved!
Confirmed Repair: The slipping pulley was causing the supercharger to spin slow and not build boost. Installed a new pulley, cleared the code and the problem was resolved.