[chzzel]

Having similar issues with my 2011 335xi as well... Just purchased the car back in September '14 and have had it parked for the winter. When the weather started to get cold back in October/November, it was start but have a very rough idle for a couple of minutes. At times the car would put itself into limp mode (no turbo) without any error codes or CEL. Yesterday I started the car like I normally do every week and it finally threw a code for me. P15df...from what it looks like, thats for the HPFP?

Surprising to me cuz I thought us N55er's were safe from that issue. Anyone else had this code thrown?

[Antetokounmpo]

I have this exact problem too. Rough idle around 620rpm then the car will bring the engine up to ~700rpm and it's perfectly smooth. It only happens in the summer. Here's a video, you can see the camera shaking when it goes down around 600rpm about halfway through the video.

[AWD Addict]

Originally Posted by parapln

Having the same saga with going after rough idle fix. This is what was done so far:
1) replaced spark plugs
2) walnut shell blasting of intake valves
3) replaced all 6 coils
4) replaced battery
5) replaced all 6 injectors (some appeared to be leaky)
6) replaced leaky valve cover gasket: it was leaking into injector's #5 and #6 bay. Old injectors were all covered with oil when I pulled them out.
7) replaced 6 fuel rails (going after fuel smell, probably the real cause was a leaky injector and not rails)
8) cleaned MAP and TMAP sensors
9) HPFP was replaced aroung 45K (now the car has 91k)
*UPDATE*
10) replaced *all* vacuum lines (including those that are attached to both turbos waste gates)

Rough idle is still there, however I do see some significant improvement in the way engine sounds now. However jerkiness is still there, no codes or warning lights. I'm not sure what to do at this point. Some people suggest replacing throttle block, but now it feels like trying to move in the dark just wasting $. I have BT and INPA cables and wonder if some parameter diagnostics could be used to find the root cause.
Does anyone have any idea which direction to move at this point?

Got me bud. I'm still there, and I've done all of that but vacuum lines (but I'm on my third HPFP - the new number now). I also have 2 new turbos replaced under the WG warranty.

[Dmacc]

Originally Posted by AWD Addict

Got me bud. I'm still there, and I've done all of that but vacuum lines (but I'm on my third HPFP - the new number now). I also have 2 new turbos replaced under the WG warranty.

Replacing boost solenoids helped my jerkiness.

[Antetokounmpo]

Originally Posted by Dmacc

Replacing boost solenoids helped my jerkiness.

Interesting.. was the jerkiness only around 620rpm while idling?

[Dmacc]

Originally Posted by bk335

Interesting.. was the jerkiness only around 620rpm while idling?

It was jerky at very low rpm ~1k or below. I'm 6MT and it was harder to start from a stop in 1st.

[LaCross]

Can somebody figure this out already lol. Im tired of my car idling like this

[Antetokounmpo]

Well, so far through this tank of gas, my car has not had a shaky idle at all. I filled up at a new station near my house this time which I never had before. It's a citgo, which I've never considered to be great gas, but maybe it could have been a gas issue, I almost always filled up at BP or Mobil when it would idle rough.

[7smurfs]

bumping this forever issue.

My car has been idling @ 800rpm when fully warmed up. It runs at 620-650rpm when warming up, however once it hits a good temperature it stays at 800rpm

Anyone ever figured this out? I gleaned through this entire thread and didn't find an answer

[Antetokounmpo]

Originally Posted by 7smurfs

bumping this forever issue.

My car has been idling @ 800rpm when fully warmed up. It runs at 620-650rpm when warming up, however once it hits a good temperature it stays at 800rpm

Anyone ever figured this out? I gleaned through this entire thread and didn't find an answer

I had the exact same issue as OP, switched to different gas, and so far through 2.5 tanks, it hasn't idled rough once.

[LaCross]

Originally Posted by bk335

I had the exact same issue as OP, switched to different gas, and so far through 2.5 tanks, it hasn't idled rough once.

Are you idling at 600?

[Antetokounmpo]

Originally Posted by LaCross

Are you idling at 600?

Yeah. It used to be rough just over 600, maybe 620 or so, and now it's perfectly smooth all the way down to 550 or so when the AC is off.

[motherkin]

Holy shit, I can't believe I get myself into this situation too. Car shakes at idle immediately after new spark plugs

[Rory]

I was planning on changing my spark plugs shorty and now I'm worried I'll get this problem

[matthewo]

I had a few low/rough idles with this car, mostly with the AC off. It is pretty much what the DME is calling for. for those who tune their cars, the new XDF file has idle tables and i was able to raise the target idle under all conditions about 100rpm and it is great, its pretty much sticks at 750 rpms all the time now. I know other people may have an issue that may need to be fixed, but i feel that the car is programed to idle a bit lower than it probably should, maybe they never thought to up the MT tables and left the AT values as it put less stress on the Torque converter and didn't try to creep forward too fast when letting off the brake.

[zbrit00x]

Having an issue where I have rough idle and misfires, but under acceleration and wot everything is fine. Also to note, when the AC is on idle is fine.

Changed plugs, coilpacks, some injectors, cleaned intake valves, replaced valve cover gasket. Not throwing any codes or having any other issues.
Exhaust do build up with carbon much faster now though.

Any ideas?

[optigrab]

Has anyone used MHD, COBB or JB4 to log their idle?

[LaCross]

bump

[Psyrick]

It is my honor to be able to contribute with fresh info after 14 pages.

Be sure to check the seal on the vacuum lines including/especially the connector near the oil filter housing.

Also, changing the PCV for an upgraded one from RBTurbo is a good idea, but I think that's already been discussed.

I have changed the injectors, and spark plugs in the past year as part of regular maintenance. I had VANOS related issues earlier this year that I solved by cleaning the solenoids and clearing codes. Rough idle and RPM hunting was something that became more noticeable recently, and that's what brought me to this thread. Symptoms very closely matching OP's, including passenger being the one to say "hey, wtf was that?" It is worth mentioning that it didn't stop once the engine was fully warm. Was often noticed at red lights mid-trip.

I also suffer from low boost with 30ff code showing up whenever I hold the gas down for more than a few seconds at a time. This was later attributed to misadjusted wastegate actuator rods. It was this troubleshoot that got me searching for vacuum leaks leading to the wastegate actuators. I checked the seal "manually" by popping open said vacuum hose connector, and using my mouth and breath to draw air from either end of the line and see if a stream doesn't come through. My hoses didn't let any flow, so they have good seal, so just before closing it up I looked at the O-rings on the connector and thought they looked a little permanently compressed. I gooped them up with silicone grease then closed it up. Low boost issue still present. Rough idle with unstable RPM is gone. Consistently holds stable around 600rpm at warm idle.

ONE MOTH LATER:
Stumbling idle came back. I went back to my primary suspect. I opened the connector and had a look. Rings are still greasy, bust also still worn. Perhaps my grease seal has mostly melted away by now. The hose was also off of one of its clips and may have shaken the seal. Ordering replacement O-rings from oringsandmore.com. Going with silicone 10mm i.d. with 3mm cross section. That'll be an extra snug fit with the plug being 10.5mm wide in he groove and the socket is 15.5mm. Considering putting a genuine Viton o-ring for the lower black one. They don't have the 10mm x 3mm in Viton. Maybe the 2.5mm cross section would be enough for such a stiff and resistant rubber.

[LaCross]

Interesting. I'll have to check that out

[AWD Addict]

Originally Posted by chzzel

Having similar issues with my 2011 335xi as well... Just purchased the car back in September '14 and have had it parked for the winter. When the weather started to get cold back in October/November, it was start but have a very rough idle for a couple of minutes. At times the car would put itself into limp mode (no turbo) without any error codes or CEL. Yesterday I started the car like I normally do every week and it finally threw a code for me. P15df...from what it looks like, thats for the HPFP?

Surprising to me cuz I thought us N55er's were safe from that issue. Anyone else had this code thrown?

Mine has been more pronounced since the temps started dropping too. As bad as it's been.

[AWD Addict]

Originally Posted by leokungkin

Holy shit, I can't believe I get myself into this situation too. Car shakes at idle immediately after new spark plugs

Incredible. That's when I notice it the most. I made the swap after 15k on the others, and the issue was there but not as bad.

Opted to throw in some fresh plugs, and bam, bad again. That's when it really started the first time too.

I wonder if it's a gapping issue? People running the Cobb AP report that the plugs don't last long because of "microgapping" changes...