I figured I would start a thread for my misfire problem. I've seen a bunch of others, but almost never see the solution (if any is ever reached). So I'll use this one to chronicle my issue.

My X5 started to stumble at idle a few weeks ago, and threw a code for the #2 cylinder (I can't remember the code number). Turned out that one was easily resolved with a new coil.

A few weeks passed and then a similar stumble started with the infamous P1351 code, which is misfire cylinder #5 with fuel cutoff. I switched the coil to a different cylinder and the code did not follow, so not the coil.

The code and stumble seem to pop up together only at idle. If the x5 is turned off for a decent amount of time or the code is cleared the engine smooths out. But they keep coming back.

I did a smoke test (the cigar and Harbor Freight pump method) and discovered a fair amount of smoke coming out around the DISA. New O-ring will be going in there.

I suspect that things might improve a little after that, but that the problem will not go away completely.

Other things I'm thinking about:
(1) CCV - previous owner said entire system replaced, but who knows for sure. Will check it out.

(2) Fuel Pump or Filter - I have read in other threads that fuel pumps are a common culprit for this type of issue.

(3) MAF ?

(4) There is a terrible oil leak somewhere on the bottom end (maybe CCV, maybe oil pan, I don't see any oil around the oil filter housing from the top, but still need to check from the bottom. This is not new so I don't think it is related to misfires/P1351 code, but will need to be addressed.

I will update this thread as I work through this code issue. Hopefully I will be able to post a solution for everyone to see.

Lastly, I've had an OBDII app on my iPhone for years, but am only now trying to figure out how to analyze the data it can produce. Right now I'm using DashCommand, which works fine to read and clear codes. I want to be able to run reports and all that. If DashCommand cannot accomplish that I will upgrade to OBDFusion. I will post the reports here (hopefully some of you who are knowledgeable can help me out there).

Please let me know if any of you have any insight.