surging idle?

[motogp79]

Hi all,
Ive been having some trouble with my 325is (92). The car has a very smooth idle just up to the point of when it warms up! At first it sounded like a bad MAF meter or idle speed contro valve. I changed both but have had no such luck of getting it to idle the way it should, ohhh i also changed the O2 sensor. I put it on the scanner and erased the codes, but it still runs the same. Help ! Does anyone have any clues?

[Wayne 962]

Sounds like it could be a vacuum leak that only occurs when something heats up?

Is it pulling any additional codes as you drive it? Surging idle should pull some new codes...

-Wayne

[Jared at Pelican Parts]

Check the intake boot going from the MAF to the throttle body. See if there are any cracks.

Typically, a surging idle is caused by a vacuum leak in the system somewhere.

[motogp79]

Thanks for the heads up, I did check my boot and even changed the o-rings on the valve cover vacum valve as well as the one underneath the intake. What i did find was the she was sucking air from the #6 intake port! I replaced the intake manifold seals and cleaned up the throtle body, threw a new set of plugs in and even blew out the injectorsand fuel rail! It cleared most of it up, But i am still getting a code under hard acceleration (o2 Loop over 4,500 rpm). I am leaning toward my fuel supply, maybe water in the fuel tank. I have noticed a change in performance once ethenol started being added into the gas. I think my next step is blowing out my fuel tank changing the filter and pump and adding some really good aditive in... Im all out of ideas! any other suggestions before i dive in again?

Thanks, Moto