Vacuum Leak - BMW Forum

RedlinedRU · 01-09-2005, 01:08 PM

I had a performance muffler installed and the guy left the vacuum hose that goes into the muffler just hanging out. I can hear it sucking air, and I think I might have a slight power loss. Is a power loss possible from a vacuum leak? should i plug the hose up? Help

RedlinedRU · 01-09-2005, 01:15 PM

well i just looked it up and this is what a site says about bmw vacuum hose leaks. I still don't know what to do though.

Other BMW Maintenance Parts

Many maintenance parts are mistakenly seen as non-critical. Though not true "tuneup" parts, the functions of these parts can definitely impact the benefit of any tuneup. Plus, as emission laws have gotten more stringent, these parts have become essential - if you want your BMW to pass emissions the first time around.

Oxygen Sensor (O2 Sensor): Your oxygen sensor(s) should be replaced at the recommended intervals. A worn oxygen sensor drastically changes engine settings. For more information on oxygen sensors, see the tech article BMW Oxygen Sensor Repairs

Vacuum Hoses: Many major systems depend on manifold vacuum for signals and function. All vacuum hoses should be checked and replaced as needed. Even a slight leak can cause major problems with performance; in some cases, the car won't even run if there's a vacuum leak.

Temperature Sensors: Temperature sensors for various engine functions can also be a good weekend project. These sensors control the fuel injection system, cooling system and even the exhaust system. And they can definitely be a cause of poor performance problems.

97alpineM3 · 01-09-2005, 01:22 PM

Well if it use to go there.. and it has a spot to go..and its just hanging there.. I would put it back in its home....

Les

RedlinedRU · 01-09-2005, 01:30 PM

yeah, but the new muffler doesn't have a place for it.

the muffler guys said that the bmw mufflers are top of the line because they have a valve in them that is closed until the engine heats up. the valve is used to store enging heat to heat the motor up faster. I think that hose has something to do with it, but don't know what.

Speedy-325is · 01-09-2005, 03:04 PM

yes, plug it up.

vaccume leaks WILL cause power loss.
find out where it comes from and plug it from there if you can. a long hose just chillin out is gonna be a problem later.

but im confused, i dont remember any vacume hoses going to the mufflers....could it be from the rear diff or somewhere else???? or are the muffs on a 98 waaaayy different? my 91 and 94 dont have that, and i dont recall seeing it on any of the cars that rolled into the shop.

Mark

Kevin325i · 01-09-2005, 04:12 PM

You don't got one speedy, it's only on the OBDII cars.

I think you're refering to the exhaust valve that's there for more torque so that could be your loss of power.

Speedy-325is · 01-09-2005, 04:19 PM

*huff----huff*

well i didnt want one anyway......... :nana

Mark

RedlinedRU · 01-11-2005, 04:05 PM

thanks speedy and kev and alpine!

Rooz · 01-11-2005, 04:19 PM

If I were you, I would take it back to the guy who did your exhaust and tell him to fix it...

I am saying that bcs on ym previous car, I had a true dual custom exhaust done, and one day my dad drove my car (god knows for what reason) and he thought there was something wrong with it (where there wasn't) him and his mechanic fixed "aka killed my custom exhaust job" since they didn't know how it was "duh it's a custom job, not supposed to like like anyhting you've seen before". But anyways, my point is - the guy would fix it for free bcs you paid him for a job he didn't do right all the way.

RedlinedRU · 01-11-2005, 05:02 PM

yeah thats what my dad said to do.....sounds good, but for now i just plugged it up.....seemed to get a little more power too

victorgallas · 01-19-2005, 06:12 PM

that vacuum pipe you are talking about is to open and close a a port on one of the exaust ports. the vacuum pipe is fitted on a raound thing, inside there is a round metal shaft that moves foward or backwards, to open or close the port on the exaust.

this pipe goes all the way back to the manifold, on stock exaust systems, when ever you step on the gas, vacuum is created on the manifold, but when accelerating there is a high vacuum moment, this high vacuum opens this port. this little port system was to ensure optional low end torque and top. so the engine can have a more controlled exaust system for different engine speeds.

sicne on the new exaust there is not such a device, all you have to do it to plug the pipe. and dont go to the guy who installed this complaining, because there is o nothing he can do.. yes he made a mistake of not plugin it. but still there is nothing he can do about the port opening and closing feature, only stock exaust system have this,

and if you went to your exaust and is not there, well there is an explanation. OBD 1 cars did not have this, since they where more primitive. beginning on 95/96 they had the OBD 2 system, a much advanced computer management system..

so dont freak out.. as long is plugged, your good.

and if you think this is not true, go and look for a metal "door" on one of the ports on the exaust of any e36 that is made after 95/96 .