Hi,
I am looking to buy a 2006 BMW 330XI from craigslist that has a misfire on cylinders 5&6. The car is a manual and has 145k miles on it. I already had the owner of the car check for oil in the plug holes and there was none. I also had them run the engine and remove the oil cap to check for any positive crankcase pressure that a bad CCV would have caused. Again, nothing. The owner claims to have replaced the spark plugs, but the problem still persists. According to the mechanic, the ignition coils and spark plugs were inspected. In addition, the mechanic told them that they would have to remove the valve cover gasket to see if the car needed a new engine (which I highly doubt). From what I've been told, it's rare for a 6-cylinder BMW to loose compression, especially in two cylinders at once! I'm thinking that it could either be bad coils, bad spark plugs, or bad fuel injectors. The owner also states that before the misfire, a couple of coils were replaced. Maybe the mechanic mixed the coils, which caused the misfire? I've heard that mixing coils on an N52 engine can lead to a misfire. Only the 'Service Engine Soon' light is on in the pictures. Hopefully you guys might have some insight into any other possible issues that may have caused the misfire. Just looking to get some additional advice and to see if this purchase would be worth my time. Thanks everyone!