Vacuum pipes at plenum

[my leige]

Hi,

Can anyone tell me the purpose of the two vacuum pipes that connect to the plenum immediately after the throttle body. I believe the pipe at the front is for the accoustic valve but I can't identify the one at the back, it seems to disappear behind the bulkhead sound insulation. I'm concerned about this pipe because it looks like it has got too warm from the exhaust manifold and sucked itself flat. I'm thinking that this may may be responsible for the poor idle.

Car is a Ph2 172 FF (2002 model).

 

[Will.]

I THINK it has something to do with the pressure and keeping the idle. Remove it and you car will rev to the limit.

 

[my leige]

I wondered if it was a connection for a remote MAP sensor. I know that on some cars the MAP sensor is actually in the ECU. Can anyone confirm this?

 

[Ian_s]

The MAP sensor is on the left hand side of the plenum

 

[sideways danny]

brake servo vacuum

 

[my leige]

Thanks for the replies.

I'll isolate this tomorrow to see if it makes a difference to the idle. The brakes seem fine BTW and i reckon that the pipe must be something like 70 - 80% flattened.