Diplomat V8-318 5.2L VIN K 2-bbl (1982)
Power Heat Control Valve: Description and Operation
Fig. 6
This valve is used on 1977-82 vehicles to increase the flow of hot exhaust gases through the left-hand exhaust manifold to rapidly bring the
mini-catalyst up to operating temperature. The CCEVS controls the manifold vacuum signal necessary to activate the valve. At coolant
temperatures below a predetermined level, manifold vacuum is applied to the valve and all exhaust gases flow through the left hand exhaust
manifold. Above this temperature no vacuum is applied to the valve and exhaust-gas flows through both the right and left exhaust manifolds.
Fig. 7
On 1978 California vehicles with V8 engines, a Power Heat Valve Delay Device (PHDV), Fig. 7, is used to delay the opening of the power heat
control valve to assure more positive engine warm-up. The PHDV also delays the opening of the control valve during certain acceleration
conditions which would cause the vacuum to fall below the level required to operate the control valve and keep the shut-off blade in the closed
position. During acceleration, vacuum at the actuator decreases slowly due to having to bleed down through the restrictions. Thus, vacuum remains
at a level sufficient to keep the shut-off blade closed for the duration of the acceleration period.
