[juld0zer]

Depends where the crack is. Personally i'd ask to get the thing smoke tested before forking out for a new one. Unless your rocker cover gasket is leaking aswell. Otherwise it is not an implausible explanation because the vacuum reservoir is inside the rocker cover.

Problem is, there are heaps of possible vacuum leaks on the N55.

If you've had the oil filter housing gaskets done they may have disconnected the vacuum supply pipe from the vacuum pump either by pulling the rubber hose off or unscrewing the nipple from the pump. By breaking the seal when pulling off the hose, the seal is compromised. The clip on fitting to the rocker cover is also likely to leak because it only has one o-ring, vibration can cause a leak.

The small hoses from the rocker cover to the pressure converter (wastegate solenoid) and from the pressure converter to the wastegate vacuum actuator can get brittle with age and heat. Again, if they have been pulled off before then they might not seal as good as they used to.

The hoses to the exhaust flapper can also leak like the wastegate ones. If you have done the golf tee mod then make sure the golf tee or whatever plug is still tight and present.

If you want a cheaper fix and dont mind the clutter, go buy a new N54 vacuum can and some suitable vacuum hose and replumb the system. You'll need some adapters to make it work though

[Mean E92]

Originally Posted by juld0zer

Depends where the crack is. Personally i'd ask to get the thing smoke tested before forking out for a new one. Unless your rocker cover gasket is leaking aswell. Otherwise it is not an implausible explanation because the vacuum reservoir is inside the rocker cover.

Problem is, there are heaps of possible vacuum leaks on the N55.

If you've had the oil filter housing gaskets done they may have disconnected the vacuum supply pipe from the vacuum pump either by pulling the rubber hose off or unscrewing the nipple from the pump. By breaking the seal when pulling off the hose, the seal is compromised. The clip on fitting to the rocker cover is also likely to leak because it only has one o-ring, vibration can cause a leak.

The small hoses from the rocker cover to the pressure converter (wastegate solenoid) and from the pressure converter to the wastegate vacuum actuator can get brittle with age and heat. Again, if they have been pulled off before then they might not seal as good as they used to.

The hoses to the exhaust flapper can also leak like the wastegate ones. If you have done the golf tee mod then make sure the golf tee or whatever plug is still tight and present.

If you want a cheaper fix and dont mind the clutter, go buy a new N54 vacuum can and some suitable vacuum hose and replumb the system. You'll need some adapters to make it work though

My flapper in my exhaust is unplugged from my trunk because I have a muffle delete. If I plug it back in and don't plug it up can it cause a vac leak?
Sorry if the question sounds stupid.

[hz_diesel]

Originally Posted by cwbmw

Bumping for google index because there aren't too many online records of this issue:

2011 N55 335i coupe e92lci

- In my case, no change of engine bay sound at all.
- Half engine light when building boost above ~3k rpm.
- Loss of low end and high end power, degraded fuel efficiency
- Active DME codes (need bmw specific scanner to read):

2C57 - Charging pressure control, plausibility Pressure too low.
387F - Power management: Standby current violation.

- Replaced the pressure converter:
Genuine BMW - 11747626351 - Pneumatic Wastegate Actuator

- Issue resolved, full boost restored.

Originally Posted by norsairius

I had this issue come up a while ago. Check engine light that would come on at seemingly random times, but mostly when accelerating on to highways. Car never actually felt weak though. Pulled codes and 2C57 came up for charge pressure too low. Took it to the dealership and they found that the issue was a kinked EPKS hose to the valve cover. It was an easy/cheap fix. Happened at ~47.5k miles, now at ~60k.

Mine also comes on randomly... Usually once a day and then after I clear it, no issues. Can usually go WOT and full boost but at highway speeds and a quick over 3k for lane switch I'll get the 2c57 code and half engine light. Might just try the pneumatic wastegate actuator, is there any specific way to diag it? or just replace and pray.

[Mean E92]

Originally Posted by hz_diesel

Mine also comes on randomly... Usually once a day and then after I clear it, no issues. Can usually go WOT and full boost but at highway speeds and a quick over 3k for lane switch I'll get the 2c57 code and half engine light. Might just try the pneumatic wastegate actuator, is there any specific way to diag it? or just replace and pray.

Honestly if you never replaced your pneumatic actuator then try. Because it's made from plastic and cracks easily. My boost leak got worse by time because it was the crack getting bigger and bigger. A new one fixed my leak. But a couple of months later it was a crack in my valve cover. After a new VC I was all ready to go!!

[juld0zer]

Originally Posted by Mad E92

My flapper in my exhaust is unplugged from my trunk because I have a muffle delete. If I plug it back in and don't plug it up can it cause a vac leak?
Sorry if the question sounds stupid.

Ideally in your situation i would find the vacuum supply hose which looks like corrugated conduit or plastic windscreen washer pipe and disconnect the rubber hose, then plug it. Or you can do the golf tee mod. Same thing really.

[jiatistuta]

OK I'm here to revive this post to share some of my experience and find some help.
My car is 2011 335i N55 coupe 65k miles. All stock except a VRSF chargepipe.
Codes that I've already fixed or maybe fixed (the code never pops up but some problems remain) are:
p112f (intake manifold pressure too high)---change cracked stock chargepipe and MAP sensor on it
p325f (plausibility of fuel pressure)---change high pressure fuel pressure sensor

Both codes can put the car into limp mode when I press gas pedal hard, no matter high speed or low speed. Gentle acceleration is fine. No noticeable loss of power. It's been 3 months and 1 month since the 1st and 2nd repair: above two codes never come back.

Now the car got two new codes: 2C57 (charge pressure too low) and 2906 (suspicion of leaks between turbocharger and intake valves). They dont put car into limp mode but a half engine light (disappear after restarting the car). Here is my work on the verification:

1. Clear the codes.
2. Wide open throttle (WOT) from 0mph to 60mph, no error.
3. Cruise at 60mph for a while and WOT from 60mph to 100mph, engine light is on somewhere between 80mph and 100mph
4. stop, read codes

I repeated the above process 3 times on 3 separate days, same problem, same codes (2c57, 2906)

I used an Autophix ES910 OBD reader to see the codes and datastream. Online values may fluctuate a little but the trend is firm.

• Ambient pressure: 1010hpa (14.6 psi)
• idle-3k rpm:
  • intake manifold pressure after throttle valve: 955.47hpa (13.9psi)
  • intake pipe vacuum before throttle value: 1005.23hpa (14.6 psi)
  • intake pipe vacuum upstream of throttle valve: 1005.55hpa (14.6 psi)
• 3k-4k rpm:
  • intake manifold pressure after throttle valve: 1000hpa (14.5psi)
  • intake pipe vacuum before throttle value: 1020hpa (14.8 psi)
  • intake pipe vacuum upstream of throttle valve: 1060hpa (15.4 psi)
• 4k-5.5k rpm (above 80mph, engine throws error codes here. No error below 80mph):
  • intake manifold pressure after throttle valve: quickly boosted from 1000 to 1400hpa (14.5-20.3psi)
  • intake pipe vacuum before throttle value: quickly boosted from 1020 to 1500hpa (14.8-21.8 psi)
  • intake pipe vacuum upstream of throttle valve: quickly boosted from 1060 to 1500hpa (15.4-21.8psi)

Here are my questions:

1. It looks like code 2C57 and 2906 should show up as twins? I don't know if this 2-code situation is different from the only 2C57 code.
2. Stock MAP sensor reads up to 22psi. Stock turbo boosts up to 8 psi. Considering the ambient pressure 14.6psi, the max possible boost absolute pressure read from MAP sensors is about the sensor limit 22psi. My car can boost up to 21.8psi, which looks good. However, there is no boost while cruising (below 3k rpm, MAP sensor reading <= ambient pressure). What are correct MAP sensor readings at different rpms? Anyone share their data?
3. If there is boost leak, is it possible that our cars can still get to 22psi? Any suggestions on how to do a quick and easy leak check (not pricey)?

What I will do next, is to change the pneumatic pressure converter mentioned in this post. It is prone to fail so I have to change it anyway even though it still works now. If the problem remains, I will do a thorough leak test and see what is going on. I will keep updating until it is solved (hopefully ). Any comments and supports will be highly appreciated!

[jiatistuta]

Originally Posted by jiatistuta

OK I'm here to revive this post to share some of my experience and find some help.
My car is 2011 335i N55 coupe 65k miles. All stock except a VRSF chargepipe.
Codes that I've already fixed or maybe fixed (the code never pops up but some problems remain) are:
p112f (intake manifold pressure too high)---change cracked stock chargepipe and MAP sensor on it
p325f (plausibility of fuel pressure)---change high pressure fuel pressure sensor

Both codes can put the car into limp mode when I press gas pedal hard, no matter high speed or low speed. Gentle acceleration is fine. No noticeable loss of power. It's been 3 months and 1 month since the 1st and 2nd repair: above two codes never come back.

Now the car got two new codes: 2C57 (charge pressure too low) and 2906 (suspicion of leaks between turbocharger and intake valves). They dont put car into limp mode but a half engine light (disappear after restarting the car). Here is my work on the verification:

1. Clear the codes.
2. Wide open throttle (WOT) from 0mph to 60mph, no error.
3. Cruise at 60mph for a while and WOT from 60mph to 100mph, engine light is on somewhere between 80mph and 100mph
4. stop, read codes

I repeated the above process 3 times on 3 separate days, same problem, same codes (2c57, 2906)

I used an Autophix ES910 OBD reader to see the codes and datastream. Online values may fluctuate a little but the trend is firm.

• Ambient pressure: 1010hpa (14.6 psi)
• idle-3k rpm:
  • intake manifold pressure after throttle valve: 955.47hpa (13.9psi)
  • intake pipe vacuum before throttle value: 1005.23hpa (14.6 psi)
  • intake pipe vacuum upstream of throttle valve: 1005.55hpa (14.6 psi)
• 3k-4k rpm:
  • intake manifold pressure after throttle valve: 1000hpa (14.5psi)
  • intake pipe vacuum before throttle value: 1020hpa (14.8 psi)
  • intake pipe vacuum upstream of throttle valve: 1060hpa (15.4 psi)
• 4k-5.5k rpm (above 80mph, engine throws error codes here. No error below 80mph):
  • intake manifold pressure after throttle valve: quickly boosted from 1000 to 1400hpa (14.5-20.3psi)
  • intake pipe vacuum before throttle value: quickly boosted from 1020 to 1500hpa (14.8-21.8 psi)
  • intake pipe vacuum upstream of throttle valve: quickly boosted from 1060 to 1500hpa (15.4-21.8psi)

Here are my questions:

1. It looks like code 2C57 and 2906 should show up as twins? I don't know if this 2-code situation is different from the only 2C57 code.
2. Stock MAP sensor reads up to 22psi. Stock turbo boosts up to 8 psi. Considering the ambient pressure 14.6psi, the max possible boost absolute pressure read from MAP sensors is about the sensor limit 22psi. My car can boost up to 21.8psi, which looks good. However, there is no boost while cruising (below 3k rpm, MAP sensor reading <= ambient pressure). What are correct MAP sensor readings at different rpms? Anyone share their data?
3. If there is boost leak, is it possible that our cars can still get to 22psi? Any suggestions on how to do a quick and easy leak check (not pricey)?

What I will do next, is to change the pneumatic pressure converter mentioned in this post. It is prone to fail so I have to change it anyway even though it still works now. If the problem remains, I will do a thorough leak test and see what is going on. I will keep updating until it is solved (hopefully ). Any comments and supports will be highly appreciated!

Update:

Pneumatic pressure converter changed with no luck. Finally this problem is solved by changing the turbo outlet charge pipe (between turbo and intercooler). The stock pipe is cracked.

A cracked turbo outlet charge pipe will trigger all the codes mentioned above, even including the fuel pressure error code!

[cosm1c]

Dang ya'll I'm in the same boat. Light throttle/boost at 2.5k rpm and my car throws an engine malfunction. Its fine WOT tho I think, hit like 16 psi on map 5. Mods are JB4, BMS intake, VRSF cp. My pressure converter made a weird buzzing sound after I drove hard. So I thought that was what was causing this issue. I can hear the boost leak in the engine bay too, air blowing out somewhere. But I got my pressure converter replaced yesterday and issue persists, unless he botched the install or something. Will check out my chargepipe sealing and turbo outlet I guess, driving me crazy.

[cosm1c]

Originally Posted by jiatistuta

Update:

Pneumatic pressure converter changed with no luck. Finally this problem is solved by changing the turbo outlet charge pipe (between turbo and intercooler). The stock pipe is cracked.

A cracked turbo outlet charge pipe will trigger all the codes mentioned above, even including the fuel pressure error code!

Attachment 1834927

Did you DIY?? I have a general idea where the outlet is but no idea how to access it.

[malibu60402]

My 2011 335ix recently got the 'Engine malfunction! Reduced power' message from the 2C57 code while accelerating moderately quickly. The car still ran like normal; not in limp mode. Shutting off the car and restarting cleared the trouble but it would come back predictably every time I goosed the throttle beyond a certain point.

From reading this and other posts, I ordered the Pressure Converter which now has part number 11-74-7-649-407. Replacing the part stopped the Engine Malfunction light and message plus the car had a much more spirited response to goosing the throttle. The loss of this power probably happened quite some time before this and perhaps gradually so that I didn't notice it was gone. So glad to have it back!

[njmian]

I have this issue with my n55, bone stock car. I am getting 10hg vacuum at idle and 25hg of vacuum at full throttle(tested with a boost guage tee in between the line that goes from the boost solenoid to the wastegate actuator). Car has no boost leaks, no vacuum leaks, tested multiple times, pressurized the system to 20psi and it holds. the wastegate closes all the way too. I also took off the dv and it looks like a new. Then i took the inlet pipe and things seemed fine the turbo spinned with finger. So i put a a gopro close to the turbo and watched live feed on my phone, started the car, starts up normal, the turbo is not spinning at all, give some revs and it only spins but not fast,more like a desktop fan, then stops when the rpm go down to idle After that i placed my smoke machine near the turbo and the turbo is barely sucking any smoke, so i thought maybe just maaaybe the wastegate is not fully closing so i actually closed the wastegate by hand and asked someone to give gas but same thing, the turbo doesn't spin at idle even with wastegate fully closed and at reving it spins very slow. Before all this i was hitting 8psi when i used to rev and with the airbox off you can hear the stock blow off/dv. Next thing I'm gonna have to take the downpipe off and see if the wastegate fell off or something lol or my turbo is dead but i don't think so cause the propeller shaft doesn't have any play and it spins freely. Thought someone could help cause i don't want to spend another 6hrs for the 3rd time in diagnostic and get all sweaty and dirty just to get nowhere on a side note I'm surprised the car drives normal, its slow af but no misfires or other issues the half cel only comes on in 3rd gear above 4000rpm and it goes away when i turn the car off. God these bmws are finicky

[bearhugs]

Originally Posted by jiatistuta

Update:

Pneumatic pressure converter changed with no luck. Finally this problem is solved by changing the turbo outlet charge pipe (between turbo and intercooler). The stock pipe is cracked.

A cracked turbo outlet charge pipe will trigger all the codes mentioned above, even including the fuel pressure error code!

Attachment 1834927

Sorry I know old post, I have the exact same error codes. Would you mind sharing the part #? much appreciated!
I have a 2012 BMW e84 X1 x28i n20.
https://www.turnermotorsport.com/BMW...xoCbNoQAvD_BwE

I think n20 charge pipe is connected to the engine?

[bearhugs]

OK looking closer there I found THREE pipes and I believe these are what they are called, please correct me if wrong.

1. Turbo "inlet" from air intake to front of engine
2. Turbo "charge" from cooler to driver side of engine (turbo)
3. Turbo "boost" from passenger side of engine below inlet to cooler

[wheela]

Originally Posted by bearhugs

OK looking closer there I found THREE pipes and I believe these are what they are called, please correct me if wrong.

1. Turbo "inlet" from air intake to front of engine
2. Turbo "charge" from cooler to driver side of engine (turbo)
3. Turbo "boost" from passenger side of engine below inlet to cooler

In this picture from realoem, here are the commonly referred to parts:
1. Air duct
14. Turbo inlet
16. Turbo-to-intercooler (TIC) pipe (or boost pipe)
23. Charge pipe

The charge pipe connects to the throttle body (this connection commonly fails on the oem unit). The other end of the chargepipe doesn't connect directly to the outlet of the intercooler; there is a separate pipe betwern the outlet of the intercooler and the inlet of the charge pipe. I don't know if there is a common name for this additional pipe, I'd probably just call it the intercooler outlet pipe.

[bearhugs]

Originally Posted by wheela

In this picture from realoem, here are the commonly referred to parts:
1. Air duct
14. Turbo inlet
16. Turbo-to-intercooler (TIC) pipe (or boost pipe)
23. Charge pipe

The charge pipe connects to the throttle body (this connection commonly fails on the oem unit). The other end of the chargepipe doesn't connect directly to the outlet of the intercooler; there is a separate pipe betwern the outlet of the intercooler and the inlet of the charge pipe. I don't know if there is a common name for this additional pipe, I'd probably just call it the intercooler outlet pipe.

Thanks for this detailed info. Maybe you are showing for e90?
Sorry I should have clarified my post, I looked at my own engine and diagrams to realise the different pipes. I have an n20 on a 2012 e84 X1 28i.
the airduct on mine connects to the "inlet" pipe.

[wheela]

Originally Posted by bearhugs

Thanks for this detailed info. Maybe you are showing for e90?
Sorry I should have clarified my post, I looked at my own engine and diagrams to realise the different pipes. I have an n20 on a 2012 e84 X1 28i.
the airduct on mine connects to the "inlet" pipe.

Oh sorry, I didn't realize you were n20 engine! I'm actually e84 too, but I'm n55. Under the hood, it's practicaly an e90 335ix. I just saw your post over on e84bimmers, but figured I'd already responded here. Nice to see some more e84 owners posting

[Mdilo]

Originally Posted by houtan

What tune are you running? JB4? I started to get this code while on light throttle/load. trying to figure out if its the jb4, BEF, or the sensor.

I know this is an old post but after you installed the PS2 did you have idle fluctuations and STFT bouncing + - a lot before they dialed in the tune?