Compression (V12)

Compression on V12 engine can only be checked with a BMW-specific Diagnosis and Information System (DIS). Remove engine cover. Remove spark plug from 12th cylinder. See Fig 1. Connect DIS tester. Connect charger. Call up diagnosis on DIS tester. Follow DIS tester instructions. A mechanical compression pressure check is not possible.

Fig 1: Firing Order (V12)

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