[tylerdurdon]

Hey guys, quick question for some of you more "advanced" folk out there.

I've been trying to pin down a boost issue on my 335i ('07) and am wondering if what I'm seeing is normal.

The car is completely stock and I get a limp-mode when pushing it at higher speeds (usually in 3rd or 4th between 50-70mph). It used to be only a warm weather issue and would only do it occasionally. Since restarting the car cleared it, I let it go on longer than I should have and now I really can't push the car in those ranges much unless I want limp mode.

Everything I researched suggested it's a boost issue and I'm not getting sufficient boost (car definitely does not zoom like it did), so I began with a pressure test from the hot side of my intercooler. I found a few little signs of air escaping from a couple quick-connectors, but no major leaks or anything (although I need to do it again since I didn't have a very quiet environment).

Then I saw a post regarding vacuum lines and checked them all. The ones behind the oil filter did seem a little collapsed, but not broken. I replaced them anyway but it had no effect.

This is where my question comes into play. In the thread, he says: "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." When I did this, I didn't hear any hissing or indication of a leak, but if blow long enough, I start hearing the sound of blowing through a liquid, like oil or something (a blub blub type of sound). I researched this morning and found that the main pipe I blow into connects to the vacuum pump. Is it normal for the vacuum pump to be doing that? Anyone with a normally functioning 335 want to see if theirs does the same thing?

Thanks for reading.

[bnd]

I just replaced all vac lines and found my vacuum canisters to be the weakest link. There are 2 plastic nipples or barbs on each end of the canisters that become brittle over time and will break or leak. The lines running behind the oil filter attach into the bottom of these canisters.

To replace all my lines, I ordered 15' of 3.5mm platinum cured silicone line from this site http://www.verociousmotorsports.com/...ld-by-the-Foot

I also modified my vacuum canisters instead of buying new ones.

Good luck!

[mirkwo0dforest]

How did you modify the vac canisters?

[bnd]

Originally Posted by mirkwo0dforest

How did you modify the vac canisters?

I did this http://www.e90post.com/forums/showthread.php?t=870905

I used jbweld for the barbs instead of silicone. I don't plan to remove and wanted no possibility of leaks.

OP: I missed the bottom of your post. Not sure if that's a normal sound, never checked mine, you get it figured out?

IIRC common vacuum leaks are associated with vacuum lines, vacuum canisters, boost solenoids, wastegates. Boost leaks are diverter valves, charge pipe or intercooler/pipes.Do you have codes? When my injectors were going bad, I had similar symptoms, so it may be something other than boost/vac.

[smitty513]

If your vacuum pump is failing, it won't supply sufficient vacuum to ensure proper wastegate operation but that's a pretty extreme scenario. when you disconnected the larger plastic hose behind oil filter to check for suction, did you notice any oil in the line? I have also seen that hose coming directly off vacuum pump crack and not seal properly.

[mirkwo0dforest]

thnks BND

[tylerdurdon]

Originally Posted by smitty513

If your vacuum pump is failing, it won't supply sufficient vacuum to ensure proper wastegate operation but that's a pretty extreme scenario. when you disconnected the larger plastic hose behind oil filter to check for suction, did you notice any oil in the line? I have also seen that hose coming directly off vacuum pump crack and not seal properly.

No, I didn't see any oil. I'm thinking it may be a symptom of my valve cover gasket needing to be changed. Thanks for the help!