Hi, I'm not as fluent as Ken on MINI, But, here is my OBD 1 and 2 related "checklist" for misfire related codes. If possible, get the wiring pathways all checked for all of the CYL 1 items you've worked with. More and more lately, the intermittent or problematic CEL related stuff is traced back to the wiring or it's connectors. Consider spraying all of your connectors with CRC electronic contact cleaner which leaves no residue when dried. Then, with two extremely bright lights on the subject, trace all wires as far back into the wiring loom as you can go. Since it is effectively fall now, perhaps do all four Coil Packs, spark plugs and their boots, connectors, and all four Fuel injectors as well. And upon reconnection of the connectors, apply an extremely small amount of dielectric paste to aid in future preservation of the connection. (think tip of toothpick level of paste) I'll look forward to hearing of your success, and what you'll find. Finally, believe it or not, replace your 1 , 2 , or 3 Oxygen sensors with very high quality sensors. Best, MSH

It seems you have addressed all the obvious suspects. The only other areas that comes to mind are:

1. carbon buildup at intake valves
2. burnt exhaust valve
3. pcv defect
4. dme / ecu defect

All of the above are 'educated guesses' based on our experience and other reports. Maybe a shop with the MINI ISTA diagnostics can pinpoint the possible cause...

Let us know what you find out!

Hey everyone, new to the page and have a problem with a 2008 Mini Cooper base that we cannot figure out. Bought the car with the code for cylinder 1 misfire. Replaced all the spark plugs and coil packs. Replaced cylinder 1 fuel injector. Replaced several components of the evap system. Did a compression test on each cylinder and the all hold pressure. We clear all the codes, start her up, runs fine, then take her for a test drive. After doing all of this, the car begins to misfire again, at idle, only after driving it for about 3-5 miles. The CEL comes back on and the code for cylinder 1 misfire reappears. It seems like the misfire presents itself again only after the engine gets warm. We even did a compression test after driving her to see if it was loosing compression after heating up…it still has compression. Any suggestions or info would be of great help. Thanks