Really odd noise when first accelerating - drivetrain possibly? (with video)

[halik]

I figured I might as well try it here also; I've got a really peculiar noise on my '02 911 4s:

I've started noticing really peculiar noise on my 4S tiptronic. When the car is first started and you give it a bit of gas to roll forward, I hear what I can best describe as a bike spoke clacker noise (3 metalish on plastic sounding clicks) coming from the front, somewhat leftish area of the car.

This happens only once and I cannot recreate it again until I turn the car off. Also the noise doesn't appear until I give it a bit of gas in drive (drivetrain moves quicker than idle); it will not appear if I'm creeping around while covering the brakes. I can recreate it every time by just turning the car on and off and then rolling forward with gas.


At 3 seconds you can hear it. Almost sounds like someone sticking something into spinning fan blades.
http://www.youtube.com/watch?v=OSe0sQ2uE6A
http://www.youtube.com/watch?v=3fIAvVFvkVo

 

[Railgun]

I can't see the vid at the moment, and I don't know the layout if the car, but where is the abs module? It sounds like, based on the description, it's initializing.

 

[HowlerMonkey]

Railgun is correct.

 

[halik]

I can't see the vid at the moment, and I don't know the layout if the car, but where is the abs module? It sounds like, based on the description, it's initializing.

Oooh interesting idea; why would it initialize once I start rolling, rather than when i first start the car? I didn't think the initialization state of the ABS controller is dependent on the hall effect sensors.

I didn't have any codes last I scanned the car.

 

[LTC8K6]

IIRC, they always initialize while moving.

 

[halik]

Hmmm looks like you guys might be right:
http://books.google.com/books?id=Ra...296#v=onepage&q=abs self test porsche&f=false

 

[exdeath]

Driver is totally unaware (until reading this section). Lulz.

 

[sontakke]

May be he is just letting us all know about his 911 4s

 

[halik]

May be he is just letting us all know about his 911 4s

I made a post when I first got it.

I'll take a look and see if there's something lose on the ABS pump carrier that would make it rattle against the car chassis. The pump does sit in the front left, exactly where i hear the sound coming from.

 

[Railgun]

Oooh interesting idea; why would it initialize once I start rolling, rather than when i first start the car?

They typically don't until you're going about 10 MPH.

 

[sontakke]

Lots of car do the ABS self test when moving after cold start. I know 2000 Maxima does it when I back out of the garage. It is some what random i.e. does not do it all the time but once in a while I hear that chatter noise. The noise it makes is the same when it actually engages i.e. when ABS is active during the braking. If the noise that you hear is not similar, it could still be the side effect of the ABS pump. Why not try to jam on the brakes and get the car to exercise the ABS and find if the noise is similar.