When the knock sensor malfunctions:
* It may report false positives: The engine's computer (ECU) will receive incorrect signals indicating knock, even when none is present. This causes the ECU to retard the ignition timing excessively, reducing power and leading to sluggish acceleration. The engine is essentially being deliberately underpowered to avoid a perceived problem.
* It may report false negatives: The sensor might fail to detect actual knock. This is much more dangerous as the engine could suffer damage due to sustained detonation. While acceleration might initially seem unaffected (or even improved temporarily due to more aggressive timing), this leads to eventual engine damage.
In short, a bad knock sensor will almost always negatively impact acceleration, either by causing sluggishness due to overly conservative timing or by risking serious engine damage. It's important to get a malfunctioning knock sensor addressed promptly.
