Check the 95 F (35 C) EGR Ported Vacuum Switch (EGR-PVS),Spark Delay Valve (SDV) and Vacuum Check Valve (VCV)
Those are part of The major EGR/CSC system components .
# With a cold engine, the passage between the upper and middle ports should be open, and the passage between the lower and middle ports should be closed.
# With the engine at or above the EGR-PVS temperature (typically 95 F), the passage between the lower and middle ports should be open, and the passage between the upper and middle ports should be closed.
Spark Delay Valve
# Disconnect the vacuum lines which run to the spark delay valve and connect a hand vacuum pump.
# Operate the pump and note if vacuum can be achieved.
1. A valve with one black or white side and one colored side is good if vacuum can be built up in one direction, but not in the other direction, and if the vacuum slowly decreases.
2. A valve with both sides the same color is good if vacuum can be built up in both directions before visibly decreasing.
Vacuum Check Valve
# Connect a hand vacuum pump to the vacuum (black) side of the valve.
# Apply 16 in. Hg (54 kpa) of vacuum.
# If vacuum remains above 15 in. Hg (50.7 kpa) for 10 seconds, the valve is acceptable.
The 235 F (113 C) PVS is not part of the EGR/CSC system, but is connected to the distributor vacuum advance to prevent engine overheating while idling.
(I'm sending the diagram to your email)
Wednesday, March 31st, 2010 AT 5:12 AM