[messyhead86]

Hi

I've got a 2008 335d and the small turbo doesn't spool up intermittently. This generally happens when the car has been warmed up. I've taken the engine cover off and can't see any obvious wear to the vacuum hoses which seems to be what most others attribute as the cause, from looking at other posts.

Are there any other possible causes and if anyone has had this issue is it quite obvious that the hoses were worn? Also, is it an easy fix or better left to a garage?

Thanks

[Torqu3]

Vacuum or boost leaks are the typical culprits. Maybe your pressure converters too.

[messyhead86]

Originally Posted by Torqu3

Vacuum or boost leaks are the typical culprits. Maybe your pressure converters too.

Ok thanks. One of the boost pipes shielding has signs of oil on it. As a vacuum pipe, does it suck from the turbo and could this potentially draw oil from somewhere?

[OmahaDZL]

Originally Posted by messyhead86

Ok thanks. One of the boost pipes shielding has signs of oil on it. As a vacuum pipe, does it suck from the turbo and could this potentially draw oil from somewhere?

Thats not the type of vacuum we are talking about here...

The vacuum pump is that circular tin looking thing on the front of your engine...It creates vacuum for your engine mechanicals to move... like your turbo change over flap....

if it does it intermittently...mainly when its warmed up, you could have a vacuum hose that collapses when it gets heated up.... may need to just replace...the other possibility is theres a leak and your vaccum resiviour doesnt have enough time to build up enough vacuum over and over again to move the flap... that was what was wrong with mine....though it was due to my mechanics' incompetence

[messyhead86]

Originally Posted by OmahaDZL

Thats not the type of vacuum we are talking about here...

The vacuum pump is that circular tin looking thing on the front of your engine...It creates vacuum for your engine mechanicals to move... like your turbo change over flap....

if it does it intermittently...mainly when its warmed up, you could have a vacuum hose that collapses when it gets heated up.... may need to just replace...the other possibility is theres a leak and your vaccum resiviour doesnt have enough time to build up enough vacuum over and over again to move the flap... that was what was wrong with mine....though it was due to my mechanics' incompetence

Ok thanks for the reply. I'll have a look tomorrow with engine warmed and see if there's a hose which looks overly flexible or hot.

How difficult a job is it to replace them without the car being on a ramp and sump cover off?

[OmahaDZL]

Originally Posted by messyhead86

Ok thanks for the reply. I'll have a look tomorrow with engine warmed and see if there's a hose which looks overly flexible or hot.

How difficult a job is it to replace them without the car being on a ramp and sump cover off?

WELLLLLLL....you have to take out a lot of sht to get to most of them....but I dont think you have to get to the bottom of the engine in most cases, only the top..

problem is, it will be unlikely that you will figure out the problem just by visually or physically looking at it.......heres the good news.... on startup...the change over flap goes from open to closed.....ie forcing all exhaust into small turbo... the vacuum lines that control this go into and out of the reservoir right in front of the engine (one hose coming from vaccum source, the other going to pressure converter that then hits the actuator.).... they are just 2 small hoses about half an inch apart... BUT.....EVERYONE says those nipples are SUPER brittle...sooooo you may break one even trying to check them....

[messyhead86]

Originally Posted by OmahaDZL

WELLLLLLL....you have to take out a lot of sht to get to most of them....but I dont think you have to get to the bottom of the engine in most cases, only the top..

problem is, it will be unlikely that you will figure out the problem just by visually or physically looking at it.......heres the good news.... on startup...the change over flap goes from open to closed.....ie forcing all exhaust into small turbo... the vacuum lines that control this go into and out of the reservoir right in front of the engine (one hose coming from vaccum source, the other going to pressure converter that then hits the actuator.).... they are just 2 small hoses about half an inch apart... BUT.....EVERYONE says those nipples are SUPER brittle...sooooo you may break one even trying to check them....

Cheers for the info, I'll have a gander tomorrow when I've less beer in me.

[Yozh]

You have a vacuum leak somewhere. Follow this
http://www.e90post.com/forums/showthread.php?t=1308500

and you will have go under the car to do all of the vacuum system. Your engine mounts are vacuum controlled.

[335inDe]

I bought a $24 brake bleeder with a gauge from Advance Auto which made leak chasing wayyyy easier. Also you can connect it to the wastegate, changeover valve and pressure converters to see if they hold the boost you pump in to them. I'm in your same exact boat..my main culprit was the front pressure converter. Most of my boost is back but I still have an underlying issue where in INPA my boost is being seen by they car off the charts with an exclamation mark lol..still trying to sort that out..good luck!