So heres the short story. The timing chain/tensioner failed on my 07 mini cooper s. Pistons hit the valves...you get the picutre. I was not willing to pay $8,000.00 for a new engine so I fixed it myself. The car ran great after I got it fixed for about 7,000 miles or so. Then the car began to run very rough at idle. I figured out it was do to a cracked valve cover. I replaced the valve cover and the car ran great for about 2,000 miles. Once again the car is running very rough at idle. It runs fine at any rpm above about 1200. Engine light is on and is giving me p0301 & p1497. I can not find any vacume leaks anywhere. I did the typical plug coil and wire check...moving them around not replacing them. The miss stays is cylinder #1. I did a compression test and #2,3,4 are at 140 and #1 is at 90. I have not yet done a leak down test, I will be doing that this week sometime. I would have said maybe build up would be the cause but I put in all new valves and the head was cleaner than it was when it was brand new. I find it hard to believe that could be the problem after less than 10,000 miles. Any Ideas??? Anything would be helpfull.

 

First... sorry you got had by your dealer ...... It would've been much much less at my dealer. I have seen a few Piston skirts break off, but normally they do not have 90psi compression still. they are closer to 25-50 and sometimes 0psi. Do you have any modifications to your MINI?
Obviously the cylinder leak down is the next test you need to do. That will definitely give you a better direction to go in.

Greg

 

There are no modifications on the car. The only thing that is not stock is the oil dip stick. I put in one of those cool flexable ones.