I have a 2009 Mini S with 133K miles that suddenly developed a 100% cylinder 3 misfire (P0303 error code). I pulled the coil and plug and laid them on the block and started the car. There is a strong spark at the plug, but when I shut off the car and smell the spark plug hole (now open), the smell of gasoline is faint. I assume that injector #3 is bad or clogged.

I'm a fairly good mechanic, but have no specialty tools.

Can someone tell me how difficult it would be to replace the injector? I would probably just replace one to get it going, since I'm ready to replace the car anyway. It looks like I'll have to remove the intake manifold, but are there any "gotchas" or other words of wisdom that I need to know before I attempt this job?

 

Since its not an S you don't need the special tool to compress the cylinder seal. Best advice would be to get a Bentley manual and disconnect the battery before starting the job. The LPFP will attempt to prime if the ecu wakes up. That'll make a bit of a mess with fuel lines disconnected.

 

No matter what, it's always cylinder #3!
Charles, I'd swap another injector first & see if the fault moves.
If it does not, do a compression test - it could be just a burned valve.

 

Maybe I mis-spoke IT IS AN "S". Does that make a difference?

 

I ordered a compression gauge today from Amazon. The only ones I could borrow from the local parts stores had adapters that were too big for the Mini spark plug holes.

If I change the injector, what parts will I need besides the injector and a new intake manifold gasket? Any special tools or "gotchas"?

 

There is a "hidden" 10mm bolt under the intake manifold next to the throttle body.

Were you able to perform compression test?