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Engine knock is a very specific problem where gasoline "detonates" from pressure and not spark ignition. This usually happen when the air/fuel mixture is too lean (too much O2) or the ignition timing is too far advanced. There is a distinctive "knocking" noise associated with this problem. The bast way to describe the noise is the sound of spray paint can being shaken during hard acceleration. The problem is most often noticed during hard acceleration AND hot weather. So during winter (and cold weather) the problem might be audible (and not even exists). The short term solution is to use premium gasoline. If the use of premium gasoline defeats the engine knocking noise, that is 100% confirmation that it is indeed engine knock (and not other similar sounding problem). === Modern cars have engine knock sensor, and if engine knock is detected the timing is retard to prevent engine knocking. If your car has engine knock sensor and yet suffers from this problem it is very likely the knock sensor is defective. Otherwise the problem might be one of many things: (a) A/F mixture too lean (bad o2 sensor?) (b) spark plug too hot (c) ignition (spark) timing too advanced (d) MAP / MAF sensors - defective (e) low fuel pressure (f) dirty fuel filter (g) vacuum leak (h) engine (water) temp too high (i) air temp too high (j) octane too low (k) bad fuel injector (l) carbon hot spot (m) failed knock sensor Good luck...Possible Solution --- > The mileage has been good but the acceleration is not much beyond the 2.3. I also have always been forced to use premium gas if I want to avoid serious knocking.Report it
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