[defurr]

Twice now I have had my 2011 335i seemingly stall out, meaning the engine doesn't die, but it won't rev. So it's sitting at idle, but mashing the gas produces no discernible result. Both times, just restarting the car solved the problem. The two events were spaced a month apart, despite daily driving.

Does this sound like a potential HPFP issue? I seem to have a slightly long crank time.

OBD codes are no help: I frequently have 2DD6 and 2DD8 for Valvetronic, but that's just timing. 28A0 appeared this last time (implausible throttle angle), but not the first time it happened, so that's not a common thread. No apparent misfires or half engine light.

And yes, I run Cobb Stage 1 standard Aggressive map. Indie has said that maybe it needs better downpipes and intercoolers to accommodate this map, but I've yet to take it in, since it would be nearly impossible for them to replicate.

[defurr]

Despite seemingly having either bored the folks on this board to death, or stumped them, I do believe in the value of sharing one's experiences, so here was the outcome on this deal...

My statement that, "I frequently have 2DD6 and 2DD8 for Valvetronic, but that's just timing..." should have provoked someone to call me out on my naivete. I have since learned a great deal about Valvetronic, what it does and how it does it. There are a couple of great YT videos that speak to this, so I shall refrain from the seminar.

Suffice it to say: Valvetronic is the physical mechanism by which the throttle is actuated on these cars. So, if you're getting codes relative to it, you should expect the craziness I was experiencing.

Which, as it turned out, included lagging performance: Post-repair, my car now feels like it did with the tune on it-- except that I haven't added the tune back. It now feels like I would expect a 335i to feel, in terms of power and throttle response.

So what was wrong? On the N55, the Valvetronic motor/eccentric shaft/position sensor is all one mechanism that is inside the valve cover, unlike the N54, where it's external. Somehow, the seals inside this unit were blown and it had started to take on engine oil from the inside out. Then, a careless tech on a previous valve cover gasket replacement had failed to replace the gasket that goes over the top of vTronic component. Bottom line, it was fouling out.

Cost was about six hours of diagnosis (including removal of valve cover), another 10 or so hours to pull and replace the unit, and $500 for the unit itself. Not cheap. But, from my first three drives, it feels worth every penny. And no more Valvetronic codes.

I suppose I reserve the right to remain paranoid about the stalling recurring. But given what the Valvetronic motor is and what it does and the condition it was in, it seems highly likely that was the source of the issue.

[jt335i]

Good luck bro!

[Underground6t9]

To me it sounds like the HPFP is the culprit I had similar issues

[Flyboy161]

Sorry, I just saw this thread. You are correct, Valvetronic is the cause of your woes. The throttle body is not used on N55 motors except for "limp mode". Valvetronic does all the throttling based on variable intake lift. Good job!