Over time, wear on internal working parts of your engine will need replacement. One of the internal working parts that wear is the timing chain and timing sprockets. The timing chain and sprockets are the connecting line between the crankshaft and the camshaft. As the crankshaft turns, via the timing chain, it drives the camshaft that operates the engine's valves via the lifters, push rods and rocker arm assemblies The timing of the valves opening and closing at precise intervals is crucial for proper engine operation. As the timing chain and sprockets wear, this precise timing of the valves gradually changes, eventually to a point where replacement is necessary.
Telltale signs of worn out timing chain are:
1) Rough idle.
2) Sluggish performance and poor economy.
3) Sudden engine performance change including the inability to start the engine.
4) Intermittent backfire through the intake manifold.
5) Inconsistent ignition timing or a clattering noise coming from the front of the engine.
I hope this helps