Suspecting Vacuum leak...

[ahlem]

Check the rubber "pipe" that connects the throttle body to the AFM for cracks too. If you have the original vacuum hoses on your fuel pressure regulator with the cloth covering, take a look at the ends underneath the cloth. they may be split after 18 years. The charcoal cannister is on the left inner fender area not too far from your oil filter. It's about the size of a 12 oz. can of beer. Follow the vacuum line from the fuel pressure regulator to the point it joins the under side of the intake manifold. How long has it been since the fuel filter was changed?

[e34.535i.sport]

Had a good inspection before, and I think I may have found the problem!

I had it running and pulled out the oil dipstick - Idle took a fit and was MUCH worse... I remember reading about this but can anybody remind me what it means?

The two thin lines through the manfold are sound, and it seems the intake gasket is too (haven't had chance to get carb cleaner yet though...)

I also got the ICV off (nearly snapped the metal bracket in the process) and checked the operation of the valve, it moved freely so I gave it a quick wipe and slapped it back on.

I continued to look around and found this pipe was about 1cm off where it should be... Anyone know what it is?! I took the air pipe for the alternator off so I could picture it easier...


So I pushed it back on...


Then I hit the JACKPOT I HOPE, (or lucked out as you guys call it?!) and noticed this ripped hose... I don't know what it is or where it attaches though, it is quite thick and under the throttle body/fuel rail area which is where a lot of the wierd noise is coming from... Have a look what do you think?


And another...


Please tell me this could be it, I'm really excited about having a nice idle that doesn't vibrate me off the seat!

[e34.535i.sport]

Check the rubber "pipe" that connects the throttle body to the AFM for cracks too. If you have the original vacuum hoses on your fuel pressure regulator with the cloth covering, take a look at the ends underneath the cloth. they may be split after 18 years. The charcoal cannister is on the left inner fender area not too far from your oil filter. It's about the size of a 12 oz. can of beer. Follow the vacuum line from the fuel pressure regulator to the point it joins the under side of the intake manifold. How long has it been since the fuel filter was changed?

Hey, Fuel filter changed in last 3k mile or so, badly needed doing as it had 1993 stamped on it and it was really heavy in comparison to the new one I put in!

I checked that hose you speak of fron the FPR but on mine there is no cloth covering. There is a cloth covering on the hose that goes to what I think is called a check valve? I'll post a pic later on today of it as the cloth has frayed and may be letting air in but I dont know...

Thanks for the info on the charcoal cannister, I'm going to have a look at that in a minute see if I can find it. The noise seems to come from close to the firewall but I know sounds can be deceiving.

Report back later...

[bmwpower]

Check the nipple on your brake booster hose check valve. It's supposed to have a rubber cap on the small nipple. Mine was recently cracked and I could hear a definite sucking sound, almost a whistle, when running.

That big "hose" is not a hose but a wiring loom... or at least I think it is since it looks like it's going into the wiring harness box.

Those other hoses are power steering lines.

[Sixdown]

The first two images look like the power steering hoses, but I am not sure if anything in that vicinity is a vacuum hose.

[e34.535i.sport]

Check the nipple on your brake booster hose check valve. It's supposed to have a rubber cap on the small nipple. Mine was recently cracked and I could hear a definite sucking sound, almost a whistle, when running.

That big "hose" is not a hose but a wiring loom... or at least I think it is since it looks like it's going into the wiring harness box.

Those other hoses are power steering lines.

Hey thanks... I thought they were powersteering lines as the big one in the picture goes to the PS pump, but the other one that I had to push back on goes straight to the front (by the grill somewhere) and the other end goed under the engine to the other side I assume...

This brake nipple sounds interesting, will have a look at this as soon as I finish work I think! Rough Idle is still a puzzler if the big ripped hose isn't it... I'm gutted.

[e34.535i.sport]

I've read around again and if the idle goes crappy when you pull out the oil dipstick its supposed to mean I have vacuum... So what the hell could the rough idle be - fuel pressure?! Don't think that would explain the whistle though...

This is a tricky one.

[AngryPopTart]

If I pull the dipstick out of my car nothing happens, but if I take the oil cap off the idle goes to crud. Also, that little check valve that attaches to the brake booster had a little hole in it, I presume where this nipple is supposed to be, and my Paps filled it with bondo cause he thought it was a leak, but I've still always had cruddy idle and I get this wierd whistling noise that changes with the shifts of the tranny, but is not the tranny whine itself. I unplugged the hole in the check valve and everything is the same, although I can put my finger over it and tell that it's got suction. Is it supposed to be plugged?

[e34.535i.sport]

Whistle turned out to be my clutch going! (See other thread for details!)

I feel like a muppet, but all the symptoms suggested vacuum leak... Grrrrr.