XJ-S V12-5.3L (1982)
Air Switching Valve: Description and Operation
Fig. 1 Air injection switching system
This system, Fig. 1, supplies secondary air to the exhaust ports only during engine warm-up.
When the coolant temperature is below approximately 100°F, the thermal vacuum valve (S) is open, causing air injection to the cylinder head exhaust
ports through the air switching valve (T). When the coolant temperature reaches 113°F the thermal vacuum valve closes, causing the air switching valve
to switch secondary air from the exhaust ports to the air cleaner.
The delay valve (R), located in-line between the thermal vacuum valve and air switching valve, retains air injection to the exhaust ports during
acceleration by inhibiting the loss of vacuum from the air switching valve.
To prevent backfiring through the exhaust system, the engine is equipped with a vacuum sensing diverter valve. This valve diverts the air normally used
for injection to the atmosphere during periods of high vacuum.
