Vacuum Limiter Valve (aka "Decel Valve"), Videos of how it operates and should be connected Options

[pbanders]

I posted on this topic some years ago, with diagrams. This post is a video demonstration of what I covered in the post referenced below.

http://www.914world.com/bbs2/index.php?sho...c=67150&hl=

Two short videos showing how the vacuum limiter valve (aka "Decel Valve") works and how it should be connected. Note the valve shown is a Volvo D-Jet valve, but they all operate the same.

Part 1

Part 2

The purpose of this valve is to limit the maximum intake manifold vacuum during overrun, which is when the throttle valve is closed while the engine is at speeds well above idle. By limiting the vacuum, it reduces stress on the MPS and the vacuum retard cell of the distributor, and may also affect the operation of the PCV valve. It also delivers a "burp" of air into the intake manifold when the throttle is abruptly shut (e.g. during shifting) that reduces emissions.

From group consensus, a setting of 16 to 18 inHg , well above the idle vacuum of about 12 to 14 inHg, is what it should be set to, so the valve does not leak at idle and affect idle setting and performance.