Missing Vacuum Tube ?

[Corpulent Tosser]

There appears to be a small tube missing from my engine, or perhaps not.
I have searched the internet for pics and some engines seem to have the tube and others not.
I noticed last couple of times I had the car out it felt like it was running rough, almost like it was running on 5 cylinders until it warmed up then it was great and wondered if the missing tube was a possible cause.

These pics are not my car, the only under bonnet I have of mine is less clear (I am not at home so can't take one at present)

If it should be there where does it go to ?

Thanks

[fatjon]

I think at some point it was deleted. It's function is to reduce fuel pressure as the vacuum increases in the manifold to give a wider dynamic range of fuel flow without very short injector opening times on over run and idle. My V8 doesn't have it either.

[Corpulent Tosser]

Thanks.