dwb993

I've had my 2013 xS coupe for almost a year now and for the whole time, I've been trying to figure out where this annoying clunk noise is originating. It would happen on acceleration/deceleration and/or over bumps but was never consistent. I am a rattle freak and in my time with this car, have come to appreciate the attention to detail in the sound deadening used throughout. I've seen lots of wire loom and bundling, foam wrapped around wires and lines, etc. So when I kept hearing this particular noise, it started to get to me that I could not reliably reproduce it. It sounded to me like it was coming from behind the dash under the passenger airbag, but I knew nothing was loose under there (I looked).

Fast forward to earlier this week. I was digging around in the engine bay installing cable ties on my grounding kit wiring when I bumped into the AC purge valve. It is located between the battery plastics and the rear of the engine cover. It has a little green cap and a small info tag on it and is attached to rubber hoses. When I moved it, it hit against the plastics covering the battery and cowl area. I immediately recognized the sound as the rattle I'd been hearing all of this time.

The valve assembly itself is a hard plastic/metal combo. However, the unit is not secured anywhere in the engine bay and the rubber hoses allowed it to move freely. So, when I applied any G forces (ie: moving the car) it would tap against the plastics and the sound would transmit straight into the cabin.

I was lucky that I had my grounding kit cables to the throttle bodies running very near the valve so I cable tied the unit to the wires. So far, I have not heard that particular rattle since I made the fix. However, I have noticed a similar rattle from the drivers side engine compartment that sounds like it is low. I'll have to take a look for any similarly unsecured rubber lines that may be thrashing around.

If you do not have a grounding kit installed, you may be at a loss for how to secure the valve assembly. A couple of options would include poking a hole in the plastics and buying an OEM cable management clip. A cheaper alternative would be to poke 2 holes in the cowl plastics and run a large cable tie through them. The assembly doesn't need to be very tight, just secured from flopping around and banging into things.

So happy now. OCD much?

You can clearly see what I am talking about in this pic. Look just under the blue wire where the engine cover curves toward the intake.

Kris9884

iTrader: (3)

I love fixing little issues, especially when they are free!

JSolo

iTrader: (14)

You sure that was it?? Maybe you moved something else. Hard to believe you'd hear that from inside the cabin.

saywat?

iTrader: (3)

i think if this was the case more of us would hear this

dwb993

I can report back that this was definitely the source of the knocking sound I was hearing. I have not heard the noise since I wire tied that AC piece. Looking at the picture and under the hood, it was contacting a heat shield which was transmitting directly into the cabin behind the dash.

I heard a similar noise toward the front of the car which turned out to be my foglight wires. With the Diode Dynamics units and their extended wires, the slack cable was bouncing around the plastics creating a very similar noise.

YMMV, but this definitely was the fix in my case. As mentioned, I can be OCD with rattles. Many people likely would not even notice some the **** I do!

User 122320

iTrader: (2)

I'm not seeing what you're referring to. Can someone draw an arrow?

dwb993