Need help diagnosing some issues (error code included)

[FSUmac]

Hello,

I have a 2001 330i with 70k miles.

For the past month, I have been getting a high pitched hissing sound for a few minutes after I start the engine cold. This sound only occurs when I press the accelerator and it increases in intensity as I push harder on the accelerator. After a few minutes of driving it goes away.

Also, the CEL has shown up about once a week with the error code P0505 (Idle Control System Malfunction).

Also, I've noticed that sometimes the engine acceleration has seemed bogged down and the car has not shifted gears as smoothly, but other times it runs perfectly fine.

I've read what I can find on the Idle Control Valve issue, which is not much. Do I need to clean it or replace it to get rid of the error code? Is this a DIY or should I bring it to the local indy shop?

Any ideas on the sluggish acceleration? I recently replaced the intake camshaft sensor due to a seperate error code.

Thanks for any advice you can offer.

[FSUmac]

anyone? bueller?

[techvet]

A bad idle valve naturally will make your idle bad, even stall your engine, and have bad acceleration. Sometimes it is just a matter of the hoses connected to it.
If you decide to replace it (I have not seen anybody just clean it and make it work), then you have to remove the air cleaner assy., the air ducts to the throttle, the disa valve at the rear of the intake manifold above the throttle valve, the throttle valve (after detaching the cable), even the vent valve---to access and remove the idle valve which is at the back of the throttle valve.
It is certainly not rocket science but it takes some patience and creativity.

[NinetyEight740]

Check the intake boot as ive seen them rip and cause the idle valve faults due to unfiltered air entering the valve.

[Steve H]

Check the intake boot as ive seen them rip and cause the idle valve faults due to unfiltered air entering the valve.

+1. no need to repeat right?

[FSUmac]

I will check that intake book. Thanks.