What is this hole in image

[JapS]

I found this hole at left of TPS in image.
This hole is capped by bolt like that.
When remove that bolt, engine is rev up normally or a little smooth.
And as revving up, this hole intake air.

What is this hole?
Thanks

[glenrobbo]

Come on you 2.9 guys, someone must be able to help with this question.

[TVRees]

On mine (S2), this "hole" has a vacuum hose connected to the fuel pressure regulator.
Not sure what it does though ??
Why do you need new TPS and ISCV ? Yours look to be in good condition.

[TVRees]

here's a pic - forgot to add to previous post.

[Marc C]

See this thread...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

On mine (S3C) it goes to the fuel pressure regulator, on mine I believe that the diaphragm in the regulator is allowing fuel to pulled past it causing idle problems when the vacuum is highest

Proving it has been tricky, as disconnectioning the vac hose doesn't result in floods of fuel, but you can sure smell it

As far as I know (and I don't know much !) if yours has been disconnected then the engine will not be fueling correctly, as the vacuum created by thiis missing hose governs fuel return to the tank

Or.... This could be complete ********

[JapS]

Thanks.
MyS idle is unstable becouse of ISCV maybe.
When same symptom, I cleaned ISCV and then improved that.