I'm getting codes P301,302, and 304 which are #1,2,4 engine cylinder misfires. I changed the spark plugs and ignition coils, but still have the same issue. The car is running rough. its a 2008 regular mini. Thank you

 

Miles ? dirty injectors maybe.

 

It only has 55k miles on it and my wife drives it about 8 miles a day

 

if it was ONLY 1 cyl. that was setting the code, and the injectors were easy to swap around, the next 'free' step would be to move an injector to another cyl. that wasn't setting a code to see if the code now stored in that new location.
However......., YOU aren't there with the above, since 3 out of 4 cyl.s are storing misfire faults. Check fuel pressure and delivery amount since so many cyls. are being affected.
You may also have gotten a poor or bad tank of gas if you're still on the same tankful when this started to happen to you and your MINI.
Do the new coils have plug boots with them, or are there still spark plug wires running from the coils to the plugs[ I'm very new to MINI, but have been a tech for almost 30 years with other European brands]
The reason I ask this, is that even stubby plug boots which attach to a coil and get put directly onto a spark plug in a direct ignition or distributorless ign. system can finally go bad even though they're not as fragile as the older plug wires.
Let us know what you find out

 

Apparently the car computer turns off the cylinder in order to prevent further damage. I had to take it to a mechanic in order for them to "turn on" the other cylinders with a test set that they use. Hope this helps other people

 

I would be inclined to say you might need spark plugs if cam timing has been confirmed on point. We have been seeing an influx of non turbo's needing spark plugs far before the 100,000 mile recommendation, many of the cars have been between 50xxx and 70xxx miles.

Fuel pressure could also be a cause, but low pressure pump failure on these cars isn't all too common.

Nick
Detroit Tuned

 

The OP states he changed both plugs and coils. So that's why I asked whether the coils are direct on top of the plugs or do they have short plug wires.
I take it that this engine isn't like the newer Direct Injection models?