Piston Noise
WARNING: This page is about a different car, the 2011 RAM Pickup and 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
It can be difficult to tell the difference between a piston pin, connecting rod, or piston noise. A loose piston pin causes a loud double knock which is usually heard when the engine is idling. When the injector to this cylinder is cut out, a noticeable change will be heard in the sound of the knocking noise. On some engines the knock becomes more noticeable when the vehicle is operated on the road at steady speed condition.