"Engine knocking" is sometimes cause by cheap gas. Boost up your octane a bit. If you are using 87....Try 93. Thats a simple solution.
You also could be lugging the engine if it makes a knocking noise as you try to accelerate after you shift. Rev it up higher, then shift.
This is the only form of "engine knocking" that I have heard of. My old car use to knock from cheap gas, put in premium, noise was gone. Now, with stickshifts, if I shift too early, sometimes the engine will lug and I will hear a knocking type sound and feel it in the clutch.
It could be something else as well. Im sure the other mods such as Random will have other ideas.
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