I keep up on glow plugs. always looked good when coming out. It only taps when injector is connected and cylinder is firing, crack the injector line and tapping stops. where do I find the tdco relearn procedure? whats the chance it stops the tap? it is number one cylinder just behind turbo (passenger side front) not the worst but not the best access either

 

Google "KOKO procedure"

You will still need a scan tool that can display the TDCO value.

 

checkin it out thanks