Knocking Noise UGH!!!

[djmilleroh]

I need a little help here, the car sits throughout the week. I went out this evening to drive the car and when I turn the key to the first position (accessory position) i hear a knocking noise for about 5 to 10 seconds. Then goes away, car runs fine and seems to be no other issues.

Any suggestions?

[Mr.Wrong]

Where do you hear it's originating from?

[JayDog747]

It's the squirrel getting into his running wheel!

Yea! where's the noise coming from? The back seat, behind the dash or the engine compartment.

[djmilleroh]

I needed that. Sounds like from the engine, I did some more research and need to look into the fuel filter. Car has 70k miles

Checked the wheels yup no squirrels. Haha

[JayDog747]

Umm..ok. But the fuel filter is behind the rear seats, in front of the rear axle. When the key is turned to on, the fuel pump engages and makes more of a buzzing or humming noise rather than a knocking noise. With 70k, it is a good time to replace the fuel filter and should help with quieting down the pump.

[icanfly]

Video the noise and post it?
that's about the only thing that will help with an internetiagnosis.

[sitting proper]

If it's a slow knocking, it could be your heater or AC unit engaging. I have that happen sometimes when the key is in accessory. Mine only happens about 3-5 times though.

[924Carrera]

I had the same thing happen to mine a couple of times and it was definitely loud enough to be alarming. Seriously sounded like someone beating on something. To me, it sounded like an underhood noise, but I also read that the fuel pump could make a "slapping noise" on startup if the filter was starting to get gummed up. I replaced my filter because I figured it probably needed it in any case, and I haven't had the issue a single time since. However, I also haven't started it that many times since then because it has been torn apart for various repairs over and over and over...

[djmilleroh]

Thanks for the responses, I am going to replace the fuel filter since this service is due. I called the local dealer since I need the part asap, gave them my vin number and they were unsure if I needed the four port or three port fuel filter. Anyone know what filter is needed on a 2006 s4.

[badger.]

Thanks for the responses, I am going to replace the fuel filter since this service is due. I called the local dealer since I need the part asap, gave them my vin number and they were unsure if I needed the four port or three port fuel filter. Anyone know what filter is needed on a 2006 s4.

Just look at it, it is right underneath the passenger rear door.

[924Carrera]

Thanks for the responses, I am going to replace the fuel filter since this service is due. I called the local dealer since I need the part asap, gave them my vin number and they were unsure if I needed the four port or three port fuel filter. Anyone know what filter is needed on a 2006 s4.

Apparently there was a weird VIN split thing with the filter and even ETKA will tell you the wrong part number on some cars (I can verify this happened to me). The filter is pretty easy to see though, so just go take a look and visually verify the line quantity.

[djmilleroh]

Update: thanks guys swapped out fuel filter this weekend and I'm back up and running.