[Paul.y]

A while back my 335i peak boost started getting lower and lower. I own a 2011 e90 335i which is fbo and mhd stage 2+. I usually peak at around 18-22psi boost. I noticed that it felt like I was underboosting so I monitored my boost with mhd and it would peak at around 17psi. Over the course of a couple weeks the peak boost would get lower and lower until it wouldn’t go over 10psi. Also, I would be getting the following 2 codes along with a “Engine malfunction! Reduced power” message if I tried to push it over 10psi.
2906 - Intake plenum: Suspicion of leaks between exhaust turbocharger and intake valves.
2774 - Air volume, plausibility: Air volume too high.

I checked most fittings on charge pipe intercooler etc and eveything was fine. I tried pressurizing the system from the intake and spray water on fittings and such to find air leaks that way and also found nothing. I did my research and I found that my vacuum reservoir might be internally cracked and if it is there would be oil in it and in the line going into it from the vacuum pump. I checked and turns out that some oil collected on the bottom of my vacuum reservoir. This led me to replace the valve cover. Upon replacing the valve cover, I still had the same problem. I then did a cigarette smoke test (which I probably should’ve done before ordering a new valve cover) and found that smoke was coming from around the vacuum pump area. I did a lot of research and the only thing I found is that the diaphragm on the nozzle of the vacuum pump can deteriorate over time. I purchased a new diaphragm and when I went to replace it I found the old one was destroyed into a bunch of little pieces. However, once I replaced the diaphragm the same exact problem persisted and I would still peak at 10psi boost. Boost builds completely fine until around the 10psi mark then I hear a wooshing sound and it throws engine malfunction message and the 2 codes. Also, the idle is very rough and when the engines cold it has stalled several times on its own. Do I need to replace my vacuum pump entirely or could it be something else? Thank you for any help.

[StellaN552011]

Bumping this old thread, did you ever fix this, I have word for word code for code the exact same problem with my boost target being 19 and wont go over 10.

[Paul.y]

Yes I found it it was actually just the pipe going down into the intercooler. The tear was in such a spot where I couldn’t spot it even with a smoke test. I got a new one from VRSF for $40 and I’m back to 20psi!

[StellaN552011]

Thanks for the swift reply, Ill double check all my connections, honestly was thinking its my fuel pump but I will check thanks again.

[GoRomeo]

Originally Posted by Paul.y

Yes I found it it was actually just the pipe going down into the intercooler. The tear was in such a spot where I couldn’t spot it even with a smoke test. I got a new one from VRSF for $40 and I’m back to 20psi!

Cool, do you have photos? This would help lots of folks here. 😊

[Paul.y]

Yeah here I attached a few photos of the pipe. It was actually rubbing up against the belt which slowly over time tore a hole in the pipe. Once I replaced it I made sure to position it in a way that it has a good amount of clearance from the belt.

[n55klap]

just found this thread as im experiencing word for word, code for code issues and I saw the pictures provided with the tear in the pipe. I am fairly new to the entire modding and tuning scene and I was wondering if there are any other pictures that can be provided or further explained because I do not know which pipe is being referenced here. Apologies for my lack of knowledge but this issue has been going on and I need this thing fixed. Any help at all is much appreciated, thank you.






2013 e93 335i n55; intake, fmic, chargepipe, high flow downpipe, stage 2+ mhd

[Paul.y]

The symptoms I was experiencing could literally mean that there’s a boost leak anywhere between the intake and the turbo. Your best bet would be do perform a smoke test with a smoke machine to pinpoint the leak. The leak I found was in the pipe that goes from the charge pipe down to the intercooler on the driver side.