[Bournefromclay]

Hello Everyone,

Full Backstory: I picked up my 2011 335i a couple years ago at the tail end of extended warranty coverage with 59,000 miles. In the experience of owning the car I guess I didn't really notice how rough it seemed to idle. I took it in to BMW and they inspected and said they sent software dumps to BMWNA and determined the car was operating within normal parameters. (I couldn't get them to confirm if they agreed that it felt rough or not.) It seemed odd to me that a straight six would be so rough (much more noticeable than my Mazda MZR I-4), but looking around various forums seem to suggest the N55 isn't always the smoothest idling engine around. My only other experience with the N55 is in X3 and X5s, which were much, much smoother, as is the N20 in the F30. It's enough of a shake to easily feel through the headrest if you put your head back against it, and constant through the seat bottom and door. It's much more noticeable with the A/C off. Idle seems to sit at about 600 RPM. I kept investigating and had it check out at an Indy specializing in BMW and they reset adaptations and said it was fine. At this point there were times the car sounded truly sick at idle, while the RPM stayed steady the exhaust note rose and fell and seemed to be stumbling. Reverse gear is much worse and the engine almost stalled several times shifting into drive. I cleaned the MAF, spark plugs/coils were changed (twice now), battery replaced, investigations lead nowhere.

New Developments: I was driving home in residential at a steady 30 and the SES came on. It went away on its own the next day, then returned a week later on the exact same street. I pulled the Code from Carley as "0028A0 throttle angle - intake manifold absolute pressure, comparison, pressure too high". Most of the research I did seemed to indicate issues with a tune, but my car is entirely stock. Finally, after two attempts to find a cause, a leak was found in the charge pipe and it was replaced, the throttle body cleaned, adaptations reset, and the codes were cleared. However, the rough idle remains, the car still stumbles in reverse and at low coasting speeds, like pulling into the garage, it still surges, though not as badly. I thought maybe that was just as good as it got, then the SES light came on, then went away, but I confirmed its the same 28A0, which also lists as P112F. I've also been having weird third gear shifts, but I don't think that is related. I know there's a ton of directions it could go, but I'm trying to build a roadmap for investigation and hoping someone might have had a similar experience.

It reminds me a bit of a vacuum leak my dad had with his Infiniti, but so far no other leaks have been found since the charge pipe. I also thought about throttle body relating to the low speed surge, but that has been cleaned and checked out by the shop. I don't have much mechanical experience, but I'd like to try and be solution oriented before taking it back to the shop for further exploration. Also, possibly related, warm starts get progressively harder with longer crank times, enough to where passengers occasionally comment on it. Probably not more than 3 seconds, but consistent and enough to worry me.

If you've made it this far, thanks so much for looking it over and sharing your thoughts, or if it sounds like two totally unrelated issues and the idle is normal for an early N55 E90.

Recap
Rough idle: improves with higher RPM, such as with A/C on, but still feels like an occasional miss at freeway cruise
Code 0028A0 P112F: stock engine with 72,000 miles
Repairs performed: Charge pipe replaced, MAF cleaned, battery replaced, plugs changed, throttle body cleaned

[nynyny]

Could be HPFP...

[111R]

Check the charge pipe to see if it's broken or has come off at either end. I've had both happen, with the latter causing rough idle/stalling at idle. I'm replacing mine with a metal charge pipe from VRSF:

http://www.vr-speed.com/vrsf-chargep...i-n54-n55.html

You have to upgrade the parts that BMW value engineered one by one. It's really annoying that they've taken this approach, as they could fix all of these cheap screw parts for a few hundred dollars.

[marcoxtv]

Originally Posted by Bournefromclay

Hello Everyone,

Full Backstory: I picked up my 2011 335i a couple years ago at the tail end of extended warranty coverage with 59,000 miles. In the experience of owning the car I guess I didn't really notice how rough it seemed to idle. I took it in to BMW and they inspected and said they sent software dumps to BMWNA and determined the car was operating within normal parameters. (I couldn't get them to confirm if they agreed that it felt rough or not.) It seemed odd to me that a straight six would be so rough (much more noticeable than my Mazda MZR I-4), but looking around various forums seem to suggest the N55 isn't always the smoothest idling engine around. My only other experience with the N55 is in X3 and X5s, which were much, much smoother, as is the N20 in the F30. It's enough of a shake to easily feel through the headrest if you put your head back against it, and constant through the seat bottom and door. It's much more noticeable with the A/C off. Idle seems to sit at about 600 RPM. I kept investigating and had it check out at an Indy specializing in BMW and they reset adaptations and said it was fine. At this point there were times the car sounded truly sick at idle, while the RPM stayed steady the exhaust note rose and fell and seemed to be stumbling. Reverse gear is much worse and the engine almost stalled several times shifting into drive. I cleaned the MAF, spark plugs/coils were changed (twice now), battery replaced, investigations lead nowhere.

New Developments: I was driving home in residential at a steady 30 and the SES came on. It went away on its own the next day, then returned a week later on the exact same street. I pulled the Code from Carley as "0028A0 throttle angle - intake manifold absolute pressure, comparison, pressure too high". Most of the research I did seemed to indicate issues with a tune, but my car is entirely stock. Finally, after two attempts to find a cause, a leak was found in the charge pipe and it was replaced, the throttle body cleaned, adaptations reset, and the codes were cleared. However, the rough idle remains, the car still stumbles in reverse and at low coasting speeds, like pulling into the garage, it still surges, though not as badly. I thought maybe that was just as good as it got, then the SES light came on, then went away, but I confirmed its the same 28A0, which also lists as P112F. I've also been having weird third gear shifts, but I don't think that is related. I know there's a ton of directions it could go, but I'm trying to build a roadmap for investigation and hoping someone might have had a similar experience.

It reminds me a bit of a vacuum leak my dad had with his Infiniti, but so far no other leaks have been found since the charge pipe. I also thought about throttle body relating to the low speed surge, but that has been cleaned and checked out by the shop. I don't have much mechanical experience, but I'd like to try and be solution oriented before taking it back to the shop for further exploration. Also, possibly related, warm starts get progressively harder with longer crank times, enough to where passengers occasionally comment on it. Probably not more than 3 seconds, but consistent and enough to worry me.

If you've made it this far, thanks so much for looking it over and sharing your thoughts, or if it sounds like two totally unrelated issues and the idle is normal for an early N55 E90.

Recap
Rough idle: improves with higher RPM, such as with A/C on, but still feels like an occasional miss at freeway cruise
Code 0028A0 P112F: stock engine with 72,000 miles
Repairs performed: Charge pipe replaced, MAF cleaned, battery replaced, plugs changed, throttle body cleaned

Can you please tell me if fixed this im having the exact same issue right now

[N54S63tu]

Any fix for this, same exact code 28a0

[JTMMO]

I've got this same issue, but pulls valvetronic error codes.