| actually see a resistance on the det line - the det sensor acts as a pull-down resistor and when they fail, they have no resistance. The knock sensor is mostly analogous to an accelerometer - it is just a weighted piezo element. When you place the knock sensor atop the engine, it is further away from the rotating center of the engine: the crankshaft. The vibration the sensor feels that much further away from the crankshaft added with the additional valvetrain noise will cause the ECU to start pulling timing when the engine is placed under load (i.e. a boosted condition). The ECU will pull several degrees of timing which really hurts the performance of the engine. In effect, the detonation sensor will work almost "too good" - picking up engine vibration and noise and causing the ECU to think detonation is occuring. Fortunately it will not have any detrimental effects on engine longevity - just lowered performance. If you have your EGR system removed from your engine you can drop the tranny and replace the sensor without having to tear down the top and front of the engine.
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