Still trying to figure out this new (to me) 1996 XJS.

When driving between 0-25MPH, I hear a rustling or whooshing sound coming from behind the dashboard in the cabin. Between 25-30MPH it fades away. Perhaps it's still there, but it's not nearly as loud, to the point where I'm not sure if it's in my head or it's just a lot quieter.

Does anyone know what I'm talking about? Perhaps related to my high idle problem?

Thanks.

 

Wild guessing but your high idle could be caused by a vacuum leak ? and what you are hearing is the air getting sucked in ?

Can you tell if the noise is coming from behind the dash (but inside the firewall) or from the engine compartment itself ?

Unfortunately your 96 has a conventional hood closing system unlike the earlier cars where you can actually drive around with the hood open 3 or 4 inches. I've done this in the past to try and isolate noises. It's amazing how you can be tricked by where the sound is actually coming from

 

I can't tell exactly where it's coming from.

I can pop the hood and drive around with the hood up a little bit. I'm not sure that will make any difference in locating the source of the sound.

Is there anything in particular I should be looking for...under the hood? Getting inside the dash will not be fun. Is there anything inside the dash (firewall) that could be causing this?

Thank you.