Yeah, so, uh...

12-13 inHG (~6 psi) of vacuum can't be good. Unless I measured it at a bad spot, which was by placing my T where the vacuum check valve on the center rear of the intake manifold is supposed to go. (the one that I'm not sure which way it was installed now... sheesh (help))

PCV valve? Intake manifold gasket? Rubber boots all over the place? I hates vacuum leaks. hates em. I need an electronic vacuum leak sniffer.

But I have a feeling this poor engine vacuum (read: vacuum leak(s)) might go a long way towards explaining my lumpy-ish idle and poor engine performance. Any takers for that bet?

Ok, back to the garage. Where's my can of starting fluid / propane?


Rolf

TIA for any more tips.

Hah!

I think that I've found it.

Certainly I found something that must be a major air leak. Now if it's the only one...

Think rubber hose, probably 13mm ID (edit ... roughly 3/4"), below the MAF, connects to a silver dohickey about 3" across (edit.. and to a steel looking pipe which appears to come out of the block), which has a vacuum line leading to the electronic switch thingee which has a vacuum line leading to the black plastic cylinder storage thing , about 2" diameter and 4" long, which has a vacuum line leading to the check valve, which has a vacuum line leading the the PCV thing.

That vague enough? Well, it has 2 non-serviceable hose clamps on it, the type that are crimped rather than worm geared.

I do believe that for the time being I am going to remove it, fix it with duct tape, and see what happens. During normal business hours I should be able to get a replacement.

Ummm, it has like a huge hole in it. I read through this thread: http://forums.bimmerforums.com/forum/showthread.php?t=644377 and I do believe that this is the same hose that he had a big ol' crack in. Hmm, though, now that I look in his thread, he claims this was a cap for him, while I'm pretty sure mine is a hose. I came in to wash my hands (forgot to put on gloves while removing all the stuff) and thought I'd post what I hope is the fix to my problem before undertaking the 'tape repair' after removing it.

Updates to come... :alright

Rolf

Rolf I am betting you have all the other common vacuum leaks our cars have as well. I would if I were you - not only go over the vacuum lines - but replace the intake Manifold Gasket and the PCV Plate gasket while you are in there. That will take care of you for the next 100k miles on those items - JT

I'll go ahead and buy those gaskets and replace them.

The thread that I linked to mentioned a vent hole on the PCV, the author stated that he was able to make the engine stumble and idle erraticaly (or stall?) by plugging that vent hole. I tried it, and I only heard a sound from somewhere around cylinder 3 (if right front is cyl 1 and right rear is cyl 4), deep inside and underneath the intake manifold. I guess that might mean that I have a bad gasket on one of those cylinder's intake ports, something like that. Dunno. Certainly my idle didn't change.

I do know that it's not really a 'while you're in there' sort of thing... so I'm happy to have found the one leaking EGR-type hose. I honestly still don't know what this hose is/was, only that it had about a 1-inch radius hole in it...

I'll see where this gets me, as soon as I button things up. One thing lead to another, removing the intake parts reminded me to check the belts, looking at the belts after removing the fan and the shroud (see my 'special tool thread, by the way) showed me that one of the rubber mountings for the auxilliary water pump was broken. After fixing that, I decided to remove the secondary throttle and clean up the throttle plate with carb cleaner, etc. It's all fun, so at least I'm lucky that I have another car to drive while I leisurely clean up the easy stuff on the front end of the engine.

I really do appreciate the advice, though, and will replace those gaskets as soon as I can get them/ feel like digging deeper, based on what my vacuum gauge reads after I finish stage one.

Thanks again,

Rolf

Hi. What vaccuum gauge did you use ? Where can I order one ? I am also having vaccumm leaks but no idea how to check them. No visible hose damage anywhere. Idle is not very stable and power is less than what it should be.

Hi,

Actually, you know? Vacuum gauges were surprisingly difficult to find at the local 'auto parts' stores.

But I got this one at Sears. It's an Actron vacuum/pressure gauge. Cost $20.

Whatever I replaced helped but I'm not convinced that I've fixed everything. Transmission seems to shift a whole lot smoother now. That much is for sure.

So you did not actually identify the leak by a certain technique like carburettor cleaner or propane ? You replaced gaskets on suspected leak spots right ?