So i have a 2010 mcs hatch with a code and I can't seem to find the culprit. New valve cover/pcv, new spark plugs, new coils, new thermostat housing, and water pipe, cleaned maf, and new cam position sensor. Had quite a few issues all at once. Anyway, about a week ago it threw a p2096 code. At times it smells of unburnt fuel/rich. Its only when it's warm. Along with this is a detonation/pinning noise under heavy load "from a stop, or heavy in the throttle". Occasionally I get misfiring. All this seems to only happen when hot. It's low on power now, but before the code when I had only been driving for a short while it had plenty of power, and seemed fine. Im at 103k now but it has had oil changes every 5k. Timing assembly was done under warranty, as well as turbo replacement. I can't seem to put my finger on the source of the issue. Any help would be great.

 

Could it be carbon on the valves? Maybe HPFP? How does the car start when its sat over night

 

the car starts petfectly after sitting for even a week. The issues show up when the engine is warm. I just replaced the upstream o2, the downstream is around 30k old. The downstream voltage is jumping around a bit. I was watching it earlier while graphing it at idle. Between .2-.7.....i don't quite know why. Could an slight exhaust leak post cat cause that? I don't hear one, but it does mean there isn't one.

 

If the leak is Post cat but pre 2nd 02 sensor that very well can cause an engine to run rich. Also could be a bad sensor. Iv had them bad right out of the box. Did this just happen out of the blue or was it gradual

 

its been happening for a while now. Last 15k or so. When it's hot I have pinging/pre detonation under heavy load. Starting to wonder if i need a good combustion chamber cleaning, and while im at it intake valve blasting. It's a little rough on idle at cold start now. Not hpfp rough, but it's noticeable. Fuel pressure looks fine across the board, and no hard starting.