I Have One Sick Little Bimmer

[goonfab]

whats up...
I own a 1997 318i 5-speed and just recently I have noticed whenever it is idoling, or when you push the clutch in and disengage the engine, the revs start falling and it kinda shakes and raddles. It only does it when the car is heated though. When you first start it up, the car is fine, there isnt anything wrong with the idol, but when the car is heated to its warmth, it starts to shake and rattle when the revs fall. My dad and I have been looking at it scratching our heads. At first we figured it was the throttle control valve, but there isnt one on my car. They changed it so it didnt have one. Than we were trying to figure out whether there was some sort of vacuum leak. Whenever you turn it off, you can hear some sort of pressure, like its letting air out somewhere. If anybody has any ideas please reply...Thanks alot!

[Silverstreak]

That is definitely a vacuum leak. Get some starter fluid from the auto store and carefully spray it around areas that could be leaking (try figuring out the general area where the air noise is coming from first, have a helper turn the car on/off to locate it). When you spray starter fluid in a area where there is a vacuum leak it will disrupt the idle and make a different noise. This is how I found my vacuum leak on my intake manifold. GOod luck!

[goonfab]

Thats a good idea but, when you blip the throttle...sometimes it comes back and its fine...sorry forogt to mention it earlier. Like if you just hit the accelerator for an instant sometimes it comes back fine...sometimes it goes back to that nasty idol...

[TECH]

It does have an idle valve, but it may be the different style. It lookse like a small black box on the manifold......take a looksy.......

[goonfab]

Originally posted by TECH@Jan 12 2005, 07:31 PM
It does have an idle valve, but it may be the different style. It lookse like a small black box on the manifold......take a looksy.......

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Unfortuantley I also have a front seal leek...Yah defiantley no fun. I think we are gonna take it by the BMW dealer and have it diagnosed...but we kidna didnt want to spend the money. The shake and rattle has gotten worse. We took the throttle body off and cleaned it...and the valve sensor is an enclosed box, you cant do anytihng with it. I dunno...

[Speedy-325is]

dont go to the dealer.

go to a european indipendant shop. they usually can do alot more and alot cheaper.
it may be that your throttle cable has a bit of slack. check the BAD IDLE thread in the troubleshooting section for other ideas.

oh, when you check for a leak with starter fluid DON'T SPRAY IT!!!! light mists is enough. you are not trying to make it rev up high, just enough to hear it. try to do it with as little amount as possible because you dont want too much going through your engine if you dont have to.

[ridikuledind]

I had the same problem so i changed the O2 Sensor and the MAS. Now it runs fine.

[goonfab]

Originally posted by ridikuledind@Jan 15 2005, 08:14 PM
I had the same problem so i changed the O2 Sensor and the MAS. Now it runs fine.

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We looked at the MAS and we figured it wasnt dirty...how would you clean it...or would it be better just to replace it?