Reaper Automotive 10/31/2012Hello! Yes this code can cause the engine noise.
There can be several possible causes for a single cylinder misfire... You will need to do some testing to determine which of these things is causing the #8 cylinder misfire in your particular engine:
(1) Loss of spark. You have already replaced the plug and the coil, but have you checked to see if the plug is firing? If you remove the plug and coil, leaving them connected to the coil harness, lay the plug on metal engine surface, and crank it over you should see the plug spark. if it does not, check for battery power at one coil lead when the key is on, and for ground pulse in the other coil lead. If either of these things is not present you may have a wiring harness or connector issue, or an internal PCM fault (if ground pulse is not present).
(2) Check to make sure the fuel injector is operating. It could be making a clicking noise when the engine is running; compare it to the other injectors. Try swapping the injector with another one to see if the problem moves to a different cylinder.
(3) You may have a mechanical problem such as a leaking valve causing a misfire on the affected cylinder. Performing a compression test to check for internal engine mechanical faults is something that should be done early on in the process when diagnosing a misfire condition.
(4) You may have a vacuum leak in the intake manifold gasket near that cylinder; this would cause a very lean condition affecting only one cylinder, causing it to misfire.