All bad things come in 3's Part Deux

To recap the bad...

1. Belt tensioner fail
2. Misfire Cylinder #3 

 While I was awaiting the Amazon parts, I hit Partsource for some NGK plugs and cables. Luckily they had a sale on NGK that week :)

R53 JCW uses NGK BKR7EQUP, but after some extensive reading I decided to go copper plugs BKR7E.  Half the price of the stock plugs and copper is better conductivity.  My JCW has 100k KM on the odometer, so it was time to change. I bought the Mini used so not sure if/when the previous owner ever did maintenance.

Old plug:

 

Unfortunately the plug and wire change did not solve the misfire.  Also a rattling sound began to appear from the valve cover (uh oh..)  Which bring us to Bad thing #3.  Chain rattle.  So bad to forums for more research....

Symptoms lead to Chain Tensioner  failure.  After making some calls locally (Toronto) the least expensive place was Mini Vaughn West thanks to my SOMC club discount.

Chain tensioner install is easy enough, just have to remove a 19mm bold located next to the Oil canister.  Accessing that location is a little more difficult.

 You need to jack up the car and remove the passenger side wheel. Then remove the plastic wheel liner so you can see the bolt from the side.  However you need to access from the top side to reach the bolt with your spanner.  Torque 45 ft. pounds. New tensioner will automatically adjust once you start up the engine.

Top: Old Chain Tensioner

Bottom:New one comes compressed

this is the setup so you can get to the 19mm bolt

Picked up a coilpack from Partsource, ot fix the misfire.
 
Here are the Before and After videos.
Timing Chain rattle
New Chain Tensioner, Stabilus damper, Spark plugs, wires and coilpack installed

Bonus pictures:

Detroit Tuned tensioner stop didn't last a year :(

100k km old OEM coilpack