Funny Idle

[Gerard330ci]

Hello All.

I,m a new owner of a 2001 330ci love the car, but I have just a few questions. The exaust on this car seems a little loud for me, especially when I first crank it over. The noise sounds like it's coming from the bottom of the car, and will usually go away after about 30 seconds .Is this normal? And also my Idle seems to be acting funny it doesn't matter if the Engine is hot or cold, it gives off an up and down surging, puring, makes the car vibrate type of situation, I almost feel like it might be a fuel filter or a spark plug issue, but I can't be sure and I'm trying to avoid the Dealer $$$$. And I'm hoping its nothing to serious. One last question, what is that valve inside one of the exaust pipes meant for? And what position is it supposed to be in, Open Or closed?

Please help me !
Gerard330CI

[Two are NICE]

Gerard,

I came across a strange read related to a funny idle ... one of the causes can be a leaking O-ring on one of the injectors where it pushes into the intake manifold.

The valve you are talking about will be open under certain driving conditions, but most probably closed at idle ...

[Two are NICE]

I read something else in your post ... the noise you are describing in the exhaust, it sounds like it is that valve that stays closed for a bit and then opens ... quite possible and normal.

Other possibilities for bad idle ... air leaks into the intake tract, loose/cracked intake boot etc.

[Gerard330ci]

Thanks To All, I Do Hear A Loud Hisssing Noise When I Open The Hood Of The Car That Just Might Be The Problem,
This Is A Graet Forum Wish I Would Have Known About It Sooner, Would Have Saved Myself A Lot Of Money.

[Beachcomer]

That underhood hissing may be a ruptured diaphram in your crankcase vent valve. It's there to regulate crankcase pressure. And a bad one will result in unstable idle. Not expensive to replace.