I have a horrible hissing noise on my 01 XKR from the area below the Throttle body,is there any pipes down there that could be leaking.

I have leaning on both banks of the engine too

 

If you are running lean on both banks you might have a leak in your air intake. Not real familiar with the xkr, but lean indicates too much air after the MAF.

 

There is a breather going into your throttle elbow under the body, has a convoluted plastic pipe attached to it which goes to your lefthand bank cam cover, they often go brittle and snap/break your XK then runs like a bag of nails, there is also a take off on the same elbow on the righthand side for the brake servo, not so common for these to fail

 

XKracer is dead on, you can reach that elbow, mine was a norma connector plastic fitting (be careful) on a metal stub from the TB. To get the connector to release, I slipped a worm clamp over the line farther up the air line, then once over the norma connector 'pinchers', tightened the worm clamp, checked the connector to see if I could wiggle it off, then repeated a little at a time till it slipped off.

 

Sometimes on the older 4.0 cars it could also be one of the 2 rubbers between the V8 piece and the intercoolers. They can collapse inwards. Easy to detect if you spray a tiny bit of water over it, you will hear it being sucked in if this is the case.
The 4.2 cars have a better rubber seal, but you need also to buy plates that hold the rubber (if you need to change them).

 

Okay will check the pipe under TB,i have all ready had the seals on the intercoolers replaced with the newer versions.

See what i can find out!!!

 

Yeah can do it with about 50 miles of fuel still in tank

 

When I read the title of the thread I thought my ex-wife might be in your engine bay. On further thought, there's no way she'd fit. I'm pretty sure I can fit her body in my trunk, though.

 

Still no luck guys on this issue,can anyone think of anywhere else i could get an airleak from?

 

I think there are a few vacuum hoses that attach to the throttle body. perhaps one of those is off, or broken.

Did you pull off the intake tube to see that it's rubber seal to the throttle body is intact?

 

Get yourself a can of WD40 and spray it where you think the hissing is roughly coming from, if the engine idle picks up, thats where your air leak is.

Sometimes where you think it is, it is not, and is actually on the other side!

 

No more hissing from engine bay fixed the leak.

Surprisingly it wasnt the part load breather pipe,it turns out that a bolt had fallen out of the EGR valve and the gasket had slipped out partly too.The bolt was lying on top of the gearbox housing