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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > vacuum line fix - low boost, underboost, 30ff, wastegate rattle



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      06-18-2011, 06:14 PM   #1
mattsfeir
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vacuum line fix - low boost, underboost, 30ff, wastegate rattle

Here's a quick vacuum line fix that solved a lot of problems for me. My car's boost kept getting lower and lower, ultimately ended up around 3psi when it should have been 13.5psi. I made a boost leak tester which showed me one boost leak, but even when that was fixed, the boost level didn't change. I was getting the 30FF error code under full throttle and the wastegates really started rattling, sounded like diesel clatter.

Robert at Vishnu spent some time on the phone diagnosing the issue and said I should check all the vacuum lines, especially the ones right by the oil filter (red arrow in pic below). He also mentioned that right after shutting the car off, immediately disconnect the vacuum connector (blue arrow in pick below) and I should hear a whoosh of air being sucked in due to the vacuum. They had this same issue with a beta tester's car.

One of my vacuum lines had split right behind the oil filter, found the leak by disconnecting the vacuum connector and blowing air into it with my mouth. While that may sound weird, it was very easy to find the leak. Replaced both of the original vacuum lines with the 5/32 line from Pep Boys and all was fixed. There was vacuum when I shut the car off and boost is now back to normal.

My car is an 07 with 54k miles, as more of these cars get older and the heat from the oil filter takes it toll on the rubber lines, I'd guess more people will have this issue.

I had an appt scheduled with the dealer the next day to diagnose this, not sure what they would have charged, but I'd guess $100-$200 and the line cost $5 at Pep Boys. Great service from Vishnu giving me tips on fixing a hardware issue, Procede had nothing to do with this.

Edit: Probably best to cut the old vacuum lines off as they may be brittle and stuck to the plastic connectors. I used a utility knife to slice the ends of the old vacuum lines open (parallel to the line), then they're easy to peel off the plastic connectors. Also note that you could have a vacuum leak somewhere else besides this spot, this just appears to be a common spot.
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Last edited by mattsfeir; 06-19-2011 at 08:13 PM.
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      06-18-2011, 06:22 PM   #2
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Great information...........should be a sticky
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      06-18-2011, 06:26 PM   #3
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Great tip....thanks for that

Who would have thought that part could impact your boost pressure. But given that the vacuum cannisters control the wastegates - it kind of makes sense.

What other systems does that line provide vacuum for?

Sometimes on a cold start, my brake pedal will feel stone hard until the car starts and then it softens back to normal within a second. I think that is because of a loss of vacuum in that particular line you pointed out.
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      06-18-2011, 06:51 PM   #4
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Yup I'm the beta tester they discovered this issue on. My car would not make more than 4 psi when I dropped it off to them for the PWM meth kit install. A great easy fix. My car has only 49K on it. I strongly recommend replacing both lines to anyone who has around 50K miles or more. I bet so many have blamed their tune when it was just these lines that needed to be replaced.
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      06-18-2011, 11:12 PM   #5
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Thanks for the info. I'll replace these when i have a chance even thought I don't have any boost leak.
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      06-18-2011, 11:28 PM   #6
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Had the same issue at about 60,000klms, dealer replaced them under warranty.
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      06-19-2011, 12:38 PM   #7
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Do you have to take the engine cover off to access this?
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      06-19-2011, 12:57 PM   #8
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Quote:
Originally Posted by Palisades View Post
Do you have to take the engine cover off to access this?
Yes
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      06-19-2011, 01:09 PM   #9
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Great info!
Thank you for taking the time to share with pix.
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      06-19-2011, 03:02 PM   #10
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I'm having a hard time getting the vacuum connector off. Is there some trick to disconnecting it?
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      06-19-2011, 07:52 PM   #11
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Well I managed to screw this up. I broke the plastic tap at the red arrow when I was trying to get the hose off. My hoses were incredibly brittle and basically fused to the plastic. Now what? I guess I have to go to the dealer tomorrow morning.
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      06-19-2011, 07:59 PM   #12
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Absolutely great info Matt. Thanks.
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      06-19-2011, 08:09 PM   #13
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Quote:
Originally Posted by Palisades View Post
Well I managed to screw this up. I broke the plastic tap at the red arrow when I was trying to get the hose off. My hoses were incredibly brittle and basically fused to the plastic. Now what? I guess I have to go to the dealer tomorrow morning.
That sucks, mine were difficult to get off also, so I cut the old rubber hose with a utility knife being careful not to cut the plastic, cutting parallel to the vacuum line (slicing it open) worked for me. I'll update the first post with that info.
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      06-19-2011, 08:15 PM   #14
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Good to know, thanks.
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      06-19-2011, 09:59 PM   #15
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Quote:
Originally Posted by Ilma View Post
Great tip....thanks for that

Who would have thought that part could impact your boost pressure. But given that the vacuum cannisters control the wastegates - it kind of makes sense.

What other systems does that line provide vacuum for?

Sometimes on a cold start, my brake pedal will feel stone hard until the car starts and then it softens back to normal within a second. I think that is because of a loss of vacuum in that particular line you pointed out.
I take it the red arrow lines are boost control routed to the vacuum canisters on the passenger side. The blue arrow is the brake booster, which also has a tee to the exhaust flapper thingy. Anything else uses vacuum from the pump?
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      06-19-2011, 11:07 PM   #16
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So you IC was never leaking?
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      06-20-2011, 01:02 AM   #17
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So you IC was never leaking?
That was the boost leak that was fixed. Some pin holes in the end tank casting, they fixed it and it's back on the car now. Car feels great now that everything is working right.
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      06-20-2011, 09:10 AM   #18
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Great write up, I'm going to take a look at my lines as well!
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      06-20-2011, 03:16 PM   #19
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Quote:
Originally Posted by (-(ellblazer420 View Post
Yup I'm the beta tester they discovered this issue on. My car would not make more than 4 psi when I dropped it off to them for the PWM meth kit install. A great easy fix. My car has only 49K on it. I strongly recommend replacing both lines to anyone who has around 50K miles or more. I bet so many have blamed their tune when it was just these lines that needed to be replaced.

Yes, I remember that day I spent the morning looking for leaks, faulty wastegates, etc,.

It wasn't until I popped off a vacuum line on the vacuum tank did I notice that something wasn't right. I didn't hear the "pfffftt" of vacuum discharging. Which meant that there was no vacuum in the tank. When I tracked the vacuum lines upstream, I noticed that they were brittle. I'm surprised we haven't heard more about this on the forum. Seems to happen to some cars at ~40k miles.

Replacing these lines has become somewhat of a regular service item for all cars that go through our shop.

Shiv
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      06-20-2011, 05:10 PM   #20
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$700 at the dealership to fix the part I broke, and replace all the turbo related vacuum lines. So annoying.
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      06-20-2011, 08:55 PM   #21
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Great info OP! Thanks for sharing.

Do you guys have a boost guage? I wouldn't replace the lines unless you had a issue holding boost. Why take the chance of screwing it up?
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      06-29-2011, 07:06 PM   #22
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Quote:
Originally Posted by shiv@vishnu View Post
Yes, I remember that day I spent the morning looking for leaks, faulty wastegates, etc,.

It wasn't until I popped off a vacuum line on the vacuum tank did I notice that something wasn't right. I didn't hear the "pfffftt" of vacuum discharging. Which meant that there was no vacuum in the tank. When I tracked the vacuum lines upstream, I noticed that they were brittle. I'm surprised we haven't heard more about this on the forum. Seems to happen to some cars at ~40k miles.

Replacing these lines has become somewhat of a regular service item for all cars that go through our shop.

Shiv

Hmmm, good to know, I need to check my lines! Thanks.
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