Hi, folks. As I was pulling into my driveway today, the Mini started missing badly. While waiting for the garage door to open white smoke started pouring out of the exhaust. I first checked oil, other fluids, etc. and found no issues. There are also no fluid leaks so no blown head gasket and oil registers properly. I then pulled the codes and found a P0304 - Cylinder 4 misfire. Thinking that it must be just a plug, wire, etc. I tried to start it again to check it out. It turns over maybe half a cycle then seems to lock up and discontinues turning over. Now I'm paranoid about trying to turn it over again. The Mini has run perfectly for over two years during my ownership and I was not beating it when this occurred. What are everyone's thoughts about possible problems?

 

Pull the spark plugs - how do they look compared against one another?
With the plugs out and rotate the crank with a wrench. Can you get 2 full rotations with it binding up? Anything unusual spewing from the sparkplug holes?

 

Already checked #4 plug but it's fine -- no oil or carbon buildup -- looks perfectly normal. I'll try the crank rotation and see what happens. Here's another thought: the white smoke from the tail pipe indicates water/coolant to me. Is it possible the head gasket failed internally in cylinder 4 only and coolant entered the cylinder causing the misfire? Anyone ever run into that problem? Thanks.

 

Yes and yes.

 

SOLUTION: Pulled all the plugs and peered down in each cylinder to find gasoline floating on top the piston in cylinder #4 where the P0304 code originated. Thinking that the injector was stuck open and flooding that cylinder, I swapped all the injectors out with another set I had and problem cured. Started right up and runs smooth as glass so no bad head gasket. Whew!

 

What brand injector and curious as to how many miles on them ?

Rather odd occurence.