Vacuum Limiter

[Alberto]

I’ve been told today by an old Porsche specialist that Vacuum Limiter on my 77 991S is on its last legs.

Could someone explain what the part actually does please, I know the vacuum pipe slots on the top,, but that’s about as much as I know?

Anyone shed some light on it why it’s there what it does, what are the pipes that connect to it?

Cheers

[Lightweight_911]

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I don't know a great deal about post-'73 models but as far as I'm aware the vacuum limiter (which is also sometimes referred to as the deceleration valve) is part of the CIS emissions equipment.

I think it works by regulating rapid pressure changes in the inlet manifold when the throttle is suddenly closed - which can otherwise create increased emissions.

I'm fairly sure the original 2.4 CIS models didn't have a vacuum limiter so can't see any reason why yours couldn't be disabled/removed/by-passed if it proves to be unreliable.

Someone who knows more about CIS models will be able to confirm - or disagree ...

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