My son has a 2005 Mini Cooper S and we replaced the timing chain tensioner and a head gasket kit and now it won’t start. His car stopped running one day so we read where it might be the timing chain tensioner because when we was able to start it that it sounded horrible. When we took the valve cover off the chain was loose. So I assumed it jumped time. Now it will turn over but not start. Tested the spark plugs and they are all four firing.