I changed the spark plugs and one coil pack on my 08 MCS hardtop mini, after the change it is still throwing p0300 I thought I had a faulty coil pack on cylinder 2 after it changed the engine after unplugging it so I switched it to cylinder 1 and unplugged them one by one cylinder 2 still causes the change. It stalls when at low revs and sometimes going up a hill. the check engine light with flash if i gas it some and it will stutter but then goes back to constant after about 2500 rpm and seems to run more normal after that point. Some older mechanic in town said the battery (I do have a bad battery and will be replacing tomorrow) can cause misfires but I've never heard this. I just had the oil feed line and filter housing gasket changed, I'm at a loss, any ideas? and I have read multiple threads with similar issues but none with all the symptoms mine has together. Thanks in advance for any help.

 

Get the car to a shop that has a quality scan tool and have the codes read.

Could be low compression on one or more cylinders, HPFP failing, vacuum leak, still having a failed coil pack on one or more cylinders, improper torque on the spark plugs, could even come back to needing a thermostat.

 

heres an update, I changed the battery and verified that all spark plugs were torqued enough and went to advance and had the codes read, I'm now certain it's not the plugs or coil packs. but the codes were still misfire on each cylinder and "p0173b" and I think the other was like "P012b" although I'm not certain if that's right the tech who worked there wasn't very knowledgeable other than telling me there were 14 total codes and only gave me the two specific ones and saying the others were misfire codes and stating something about "post CAT fuel trim too rich"

 

I bet you have worn valve guides....been there, done that....we'll sort of, I unloaded it

 

Could be carbon build up on back of valves.......has it ever had a walnut blast/cleaning performed.

 

+1 inspect your valves. Just about every 50,000 miles the intake valves need to be cleaned to maintain optimum engine performance. Once the build-up reaches the maximum tolerable level, the engine will begin to run rough and misfire. You may have a rough idle, poor acceleration, stalling or single to multiple cylinder misfires. If you have any of these symptoms, check for valve residue build-up. We have a DIY that shows how we were cleaning MINI valves before MINI and BMW released the walnut blaster adapter for these engines. If you don't have the tools for the walnut blasting, this method works great as well.

What to look for (from our article).

 

article in question:

http://www.pelicanparts.com/techarti...n_Cleaning.htm