LOUD humming/buzzing noise

dailyATX82sc · 10-05-2009, 06:08 AM

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.

Its coming from behind the throttle body, a bit lower...
The car is an 82SC
ANY IDEA's??

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 · 07:39 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

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 · fritzgator's Garage

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

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

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 · Gunter's Garage

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

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)