EGR System - Low Altitude (4 Sp. Auto. Trans., Exc. Wagon

Fig. 011 EGR System - Low Altitude (4 Sp. Auto. Trans., Exc. Wagon) (Same as Fig. 48, p. 13-19):

VIN T, "A" SERIES EXC. WAGON, LOW ALTITUDE (NA5) AND 4 SPEED AUTO. TRANS.

Vacuum from the vacuum pump is modulated by the Vacuum Regulator Valve mounted on the injection pump. Vacuum is highest at idle and decreases to 10 kPa ± 3 (3.0 Hg) ± .9 at wide-open throttle. This variable vacuum then is sent to port 3 of the Transaxle Converter Clutch solenoid and port "S" of the transaxle vacuum modulator Quick Vacuum Response valve.
When the vacuum applied to any QVR valve at port "S" is constant or increasing, the vacuum output will be the same as the input. When the vacuum at port "S" drops, the vacuum on the output side is quickly vented through the vent port of the QVR, until it equals the vacuum at port "S".
The TCC (dump) solenoid prevents vacuum from passing through whenever the Transaxle Converter Clutch is engaged. When the solenoid is energized, any vacuum present beyond the solenoid is vented through the "vent" port (1) of the solenoid. When the solenoid is not energized, vacuum is applied to port 3 of the EGR Thermostatic Vacuum Switch (EGR-TVS).
The EGR-TVS is installed in a coolant passage of the intake manifold. It does two things; 1. its upper part is an electrical switch that energizes the HPCA and fast idle solenoids when the coolant temperature is below 35°C (95°F). 2. its lower part is a vacuum switch that prevents vacuum from flowing to port 2 until 41°C ± 2° (105°F ± 3.6°) coolant temperature is reached. Below 35°C (95°F) vacuum cannot pass from port 3 to 2. Any vacuum that was present at port 2 is vented through port 1. Port 1 is blocked when ports 3 and 2 are connected. Vacuum is then sent to port 3 of the Vacuum Reducer Valve and port 3 of the Altitude (TRIM) Solenoid.
The Altitude Solenoid is energized by the EGR Altitude Sensing Control switch at altitudes above 1219 meters (4,000 ft.). When it is not energized, ports 2 and 3 (of the solenoid) are connected and port 1 is blocked. Therefore vacuum at ports 2 and 3 of the VRV are the same. This causes the vacuum at port 1 of the VRV to also be the same. When the Altitude Solenoid is energized, ports 1 and 2 are connected and port 3 is blocked. Because port 1 of the Altitude Solenoid is a vent, port 2 of the VRV is open to atmospheric pressure. Now the VRV will regulate. The vacuum at port 1 of the VRV will be 8.44 kPa (2.5 Hg.) lower than the vacuum at port 3 of the VRV.
Port 2 of the Altitude Solenoid is also "T"-ed to the inlet port of the Exhaust Pressure Regulator Delay Valve (EPR-DV). The inlet port of the EPR-DV is at the end of the valve with the word CARB moulded into the plastic. When vacuum is applied to the inlet of the EPR-DV, there will be a 20-30 second delay before the same amount of vacuum is present at the outlet. Vacuum will only be available to the EPR-DV when the Altitude Solenoid is not energized.
Vacuum from the EPR-DV is now applied to port "S" of the EPR-QVR. This QVR operates the same as the transaxle vacuum modulator QVR. Next, vacuum is applied to the EPR valve. The EPR valve is installed between the rear exhaust manifold and the exhaust pipe. The EPR valve is used in the exhaust flow to increase back pressure in the exhaust system which increases the exhaust flow through the EGR system. The EPR valve should be fully closed at 43.9 kPa (13 Hg.) and open below 21.6 kPa (6.4 Hg.).
Vacuum from port 1 of the VRV is applied to port "S" of the EGR-QVR. The outlet of this QVR goes to the vacuum port of the EGR valve. The EGR valve is a vacuum modulated type. It should be fully open at 40.5 kPa (12 Hg.) and closed below 25.3 kPa (7.5 Hg.). VIN T