I found a vacuum hose not attached and can't find a place for it. Please see pics below. It is under the right rear intake and attached to the blue item in the pic. This blue (whatever) has one vac hose to the back of the manifold and this is a second hose that goes somewhere?

Thanks...Jimmy

 

Still can't find where this hose connects. For now I'll just plug it off until I can find the answer. If anyone with a V12 could take a look on theirs I would greatly appreciate it.
Thanks...Jimmy

 

Jaycee:


Is it alive??? Feel the tip or better yet, plug in your vacuum guage.


Is the engine exhibiting symptoms of a leak? Fast idle???


Not familiar with the intricacies of the V12.


Carl

 

Plugged tube, didn't make a difference with engine running. I do have a high Idle that I am working on. It's 1200 in neutral and 900 in gear.
Thanks...Jimmy

 

On the right side of the engine, under the intake and along side the block there are many hoses. Most of them connect to valves and "T's" related to the air pump, idle speed, cruise control and air conditioning.

I will try to find the hose drawings and post them here.

Remind me...what year is the engine you are working on?

Mark

 

There are two vacuum lines on top of the intake manifold, one connects to the metal line that bridges over to the manifold on the other side. The other one loops underneath and connects to the brown plastic dump valve. I think that's the one you're holding.

Let me know if you need more pics. Also, if you google jaguar Xjs vacuum routing diagram or similar, you should find a website that shows all the variants. I know I've posted that link here on these forums as well

 

Safari...Thanks.
It's a 1994 XJS V12 6.0L Convertible

 

Thanks Warlock...I'll see if I can find the hose drawings. The brown dump valve, is that the one in the second pic? I don't have that. Probably slight differences in our engines.
...jimmy

 

The brown valve is the vacuum regulator. The dump valve is at the front of the right hand cylinder bank.

 

Jal1234...So does the open hose go to one of those?
Thanks...Jimmy

 

OK...found where the vac hose goes. Good news, It goes to the air switch valve. Bad news, the air switch valve is located between the engine and the firewall about 10 inches below the heater control valve. I could almost touch it with a very long screwdriver.

Does anyone have a good description of the purpose of the Air Switching Valve? I may have to leave it disconnected until the next time I pull the engine.
Thanks...Jimmy

 

Hard to say with out knowing what the other end is connected to. There should be vacuum hose diagrams on the underside of the hood. There are several T's and connections in the general are where the regulator is.

 

There can be two air switch valves (actually vacuum valves) they are blue plastic shown in earlier photos, look the same but operate differently. One is normally closed and opens when power switched to it, the other is normally open an closes when powered.
Can't remember which is which, one does deal with hot starting by controlling fuel pressure (increase fuel pressure if fuel temp switch is indicated high fuel rail temp. The other (think situated at rear of engine) controls air injection into the exhaust manifold for a short duration (45 secs ?) After engine start up to speed up catalyst getting up to operating temperature quickly.
My 1993 6.0 l UK model doesn't have air pump fitted so only has one vacuum switch I believe