Quote:
Originally Posted by 911hillclimber
I imagine it is the way the XDi unit 'clocks' the TDC via the 2 missing teeth on the crank pulley wheel.
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Same as a 964/993.
Quote:
Originally Posted by 911hillclimber
The missing tooth gap is clocked by the crank sensor when the crank rotates and the count then starts. The command to spark to a given set of plugs in the firing order than commences.
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So the XDI system basically develops arbitrary cylinder sparks until it sees a change in RPM, at which time it synchronize the timing to the TDC signal.
This method is used by Porsche in the Cayenne engine.
Based on your problem and how the XDI functions, the ECU is not detecting any timing match to begin proper timing, even though it's receiving a crank timing signal.