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-   -   LOUD humming/buzzing noise (http://forums.pelicanparts.com/porsche-911-technical-forum/503181-loud-humming-buzzing-noise.html)

dailyATX82sc 10-05-2009 06:08 AM

LOUD humming/buzzing noise
 
So after getting something wet(see other post), i now have a loud humming/ buzzing noise all the time. Even with the key off and out of the car i still get this buzzing. :eek:

Its coming from behind the throttle body, a bit lower...
The car is an 82SC
ANY IDEA's??http://forums.pelicanparts.com/uploa...1254751608.jpg
http://forums.pelicanparts.com/uploa...1254751622.jpg

4sd911 10-05-2009 07:10 AM

Fuel pressure? Maybe you didn't notice it before.

ossiblue 10-05-2009 07:25 AM

+1 on fuel pressure. That is in the area of the return line from the Fuel Distributor and you may be hearing the dropping of pressure especially since you hear it with all electrical off in the car. Have you measured your residual fuel pressure? You may have a fault in the system that's allowing a too rapid drop of system pressure after shut down.

dailyATX82sc 10-05-2009 07:34 AM

Ive heard it before, but this time it stays on for a while. If i disconnect the Bat it turns off?? what is the sensor that is pluged in to the harness in the top pic?? when i unplug that it stop's also

ossiblue 10-05-2009 07:52 AM

Quote:

Originally Posted by dailyATX82sc (Post 4935969)
Ive heard it before, but this time it stays on for a while. If i disconnect the Bat it turns off?? what is the sensor that is pluged in to the harness in the top pic?? when i unplug that it stop's also

Okay, new information. It does appear to be electrical. Someone familiar with your year car should be able to answer the question, and it appears it is unrelated to the water episode, unless the water caused a short somewhere which is continually supplying power to a component that should be "cold" with the ignition off. You did say the water hit your DME? That component may be the cold start valve which should not be operating nor receiving power unless the engine is cranking.

fritzgator 10-05-2009 09:12 AM

I think it's the frequency valve, which bleeds off fuel pressure in the lower FD chamber thus lowering pressure to injectors. it's controlled via the o2 control unit under the pass. seat:( Taken from the Bentley manual sec 240-30)
you might want to pull that control unit out ASAP and flush it with some electronic contact cleaner and let it air dry a day or so. same with O2 relay, or replace O2 relay. Bummer.

dailyATX82sc 10-05-2009 12:35 PM

yeah that area got soaked yesterday, thats where ill start....



Quote:

Originally Posted by fritzgator (Post 4936185)
I think it's the frequency valve, which bleeds off fuel pressure in the lower FD chamber thus lowering pressure to injectors. it's controlled via the o2 control unit under the pass. seat:( Taken from the Bentley manual sec 240-30)
you might want to pull that control unit out ASAP and flush it with some electronic contact cleaner and let it air dry a day or so. same with O2 relay, or replace O2 relay. Bummer.


dailyATX82sc 10-06-2009 05:50 AM

Quote:

Originally Posted by dailyATX82sc (Post 4936554)
yeah that area got soaked yesterday, thats where ill start....

On the way home the car started to run like crap again...now i can't hear the frequency valve at all...I replaced the relay under the seat...and put a fan to blow under it and try to dry it some( it felt pretty dry).....I have checked the dizzy and it is dry...

where should i start after that??:(

Gunter 10-06-2009 06:10 AM

I would disconnect the multi-plug and remove the Lambda brain with the relay from under the seat, carefully open it, inspect and dry it out.
Dry and clean the pins, use dielectric grease and put it back together.
Fuse for the Lambda brain is the same one for interior light, clock, etc.
The Frequency valve is controlled by the brain and has to work properly for the engine to run.

dailyATX82sc 10-06-2009 06:37 AM

Quote:

Originally Posted by Gunter (Post 4937861)
I would disconnect the multi-plug and remove the Lambda brain with the relay from under the seat, carefully open it, inspect and dry it out.
Dry and clean the pins, use dielectric grease and put it back together.
Fuse for the Lambda brain is the same one for interior light, clock, etc.
The Frequency valve is controlled by the brain and has to work properly for the engine to run.


cool, thank you......that was my next step...ill remove the seat and make sure its all dry under there, then remove it and dry it real good... Ill also check all the fuse's while im at it....( now that you mention it my clock has stopped working too)


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