007 S4

I am getting an annoying whining noise coming from behind me when i am under load. It sounds almost electrical. It changes pitch (gets deeper) as load/throttle increases. What could it be?

It is audible inside the car, and outside. It is also more prevalent when the car is cold.

AxelS4

Check your fuel pump. Since you are running Stage 3, it has to deliver more fuel anyway.

007 S4

does this mean my Fuel Pump is about to take a dump?

S4mulater

next time ask your man to pull out before your wife sees you two together No more noise.

007 S4

no wife jokes, please. =(

S4mulater

sorry, boyfriend jokes ok ? (sorry it's late)

Mike S

The S4 fuel system, as with most imported cars, is a return pressurized system, meaning, the fuel pums flows FAR more fuel than you could ever need, and the extra fuel is returned to the fuel tank from the fuel rail.

The OEM fuel pump/system also supposedly carries about 3 times what is needed.

The fuel pum is readily accesible from inside the car in a slotted opening in the rear outside the right rear (if memory serves me right) shock tower.

007S4, you can have someone ride back there and listen, though I highly doubt this is what you are hearing.


Mike S

zon

i immediately thought of a bad grounding to the speakers. since that is exactly a whining noise that goes with the throttle.

AxelS4

Mike, you are correct. The pump is designed to generate more pressure than required. The excess goes back into the system. However, with stage 1, 2, 3 and so on you blow in more air into the engine, which means to get lambda be in the desired range you have to deliver more fuel (= you drain more out of the pressurized system) than in stock configuration.