Deceleration Valve

This valve is used on 2.8L engines to prevent backfiring in exhaust system during deceleration. Valve is normally closed, but opens when manifold vacuum increases during deceleration.

Vacuum overcomes spring pressure allowing additional air into intake manifold to prevent an overly rich mixture from entering combustion chambers. Air trapped in chamber above vacuum diaphragm will bleed, at a calibrated rate, through delay valve portion of integral check and delay valve.

This reducing vacuum acts on diaphragm. When vacuum load on diaphragm matches spring load, valve assembly closes. This shuts off air to intake manifold.