[carlsontheflyer]

I am glad this thread has been resurrected. My car (2010 e92 335i 6MT) also shows unusual idle behavior. the only mods I have are Cobb AP flashed, Cobb FMIC and BMW axle-back performance exhaust. This behavior persists even when I flash my car back to stock.

After a cold start, my car idles first at 1000, then drops to 800, then to 650, which is absolutely normal. It continues to idle at 650ish until it warms up. When oil temps reach around 200 degrees, all of a sudden my idle goes up to 800 and stays at 800 as long as the engine is warm.

And the entire time, at idle, every 20 seconds or so I can feel a momentary slight engine studder, as if it lightly clears its' throat. No codes what so ever, and the car runs perfectly otherwise. Never stalls, and pulls well at partial throttle, and like mad at WOT.

This has been going on for well over a year, and noone can figure out why. It's been at the dealer several times while under warranty and no problems were found.

However, last December, at around 44k miles, the HPFP failed during a hard pull. It went into limp mode and the code was "Cylinder injection shut-off" (I cannot remember the actual code). I turned off the engine, started it back up after a few minutes and it ran well, no limp mode, but the code stayed.

Took it to the dealer and they replaced the HPFP. At the same time they told me one of the injectors was leaking, so they replaced all 6 injectors with the latest ones, and also all 6 plugs and coils.

The car ran perfectly for a little more than 3 months after that. Smooth idle, and always at 650. But recently, about a month ago, it began doing the same damn thing all over again. I can again feel a slight studder every 20 or so seconds, and again, once the oil temps reach about 200 degrees the idle goes up to 800 and stays there.

Also, the intake and valves were walnut blased at 35k miles, and numerous smoke tests were done to try to find any vacuum leaks, but none were found. The car has 49k miles right now.

I am stumped, and it seems everyone else too. Any ideas?