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I don’t know what to make of this. My ’88 740 turbo has persistent pinging when under moderate load or acceleration. The car runs very well except for some stalling at cold idle. An examination of the usual list of suspects reveals the following: I always use high octane gas. A timing light shows firing at 10 deg. BTDC at idle (600rpm). At 900 rpm it jumps to 20 deg., at 1000 it is 24 deg, and above 1500 it is 25 deg. BTDC. I replaced the knock sensor with a used one- a resistance test shows infinite resistance on both and the replacement had no effect on the pinging. A disconnected knock sensor has no effect on pinging. I ran the first two procedures outlined in FAQ for “Testing Hall Sensor” as follows- the tack needle does jump, but the voltage test for red and blue show no voltage drop to ground as described in the FAQ. I have not checked the voltage behavior at the control unit since the car runs so well and this test seems difficult and risky. I would think that a car with a bad hall sensor would not run this well. The car does not generate codes. Any insights?