I recently bought a used 2011 cooper s hatchback 6 speed manual. I love it but it is giving me headaches. The day after I brought it home I gave the keys to my mom to give it a drive . Not knowing that you need to squeeze the handle to open the door she kept pressing the unlock button on the key fob thinking it was still locked. For some reason this caused the wires from the post cat o2 sensor just behind connector to glow bright red and smoke almost catching fire. I took it to my local mechanic and he couldn't figure out why and thought maybe some kind of feedback caused it and to keep an eye on it. Fast forward a few weeks later and I'm driving home from work one night and it has a major loss in power. I limp home and take it to my guy the next day and he puts his diagnostic computer on it and he determines that two of the ignition coils are bad. He replaces all four and all the spark plugs. I also had replaced the o2 sensor. It now runs fine except when you accelerate hard it misses on the first cylinder . Any ideas? Could what ever caused the initial o2 problem fried my ecu or was it a symptom and I have bad ecu that caused the problem or is it something else entirely? Any ideas would be greatly appreciated, thanks!

 

Going out on a limb here as I thought the secondary O2 sensor is preheated electrically when the ecu powers up but it may be tied to a trigger signal from the CAS to unlock the vehicle. Perhaps continuously pressing the unlock button caused the system to keep trying to preheat the sensor causing the wires to overheat.

Check the gap on the #1 cylinder plug. They're not always gapped correctly from the manufacturer. Could also be the new coil. Try swaping it with the #2. It's rare but even new parts can be bad sometimes.

 

Thanks, I'll give it a try