The engine makes a tapping sound while idling, and gets louder when accelerating.
The design of this engine often leads to sludge build up, even when regular maintenance is performed. This can cause oil restriction. The hydraulic lifters inside the engine are oil dependent, and will not "pump up" without proper oil supply. This causes abnormal slack in the valve train, which can lead to the tapping noise you describe. I suggest you have a trained professional, such as one from YourMechanic, run a diagnostic inspection of the noise to confirm whether this is your problem.
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