5000CD Quattro Wagon (Canada) L5-2226cc 2.22L SOHC Turbo (MC) (1986)
Fig. 43a Ignition Advance Strategy
If a cylinder develops ignition knock (detonation or "pinging"), the control unit will detect this through the knock sensor. The control unit will then
retard the ignition timing by 2.6° increments (up to 7.8°) until the knocking is stopped, Fig. 43a. Once the knocking has stopped, the timing will be
advanced back towards its normal value in 1.3° increments.
To prevent erroneous readings, the knock sensor signal will only be processed when the engine is in the operating range where ignition knock can occur.
These are when:
Engine coolant temperature is above 70°C (158°F)
Intake manifold pressure is above 0.7 bar (from 7 in. of vacuum to full boost)
Idle switch open