DESCRIPTION
To reduce NOx emissions, all vehicles are equipped with an exhaust gas recirculation (EGR) system. The EGR system recirculates exhaust gases from an exhaust port in the cylinder head to a port in the intake manifold located below the carburetor. EGR flow is controlled by the EGR valve and thermo valve.
EGR CONTROL VALVES
Increased EGR flow (which adversely affects driveability) is required to meet stringent emission standards. The EGR control valves compensate for the EGR system's effect on driveability. The amount of vacuum is controlled by throttle opening. The EGR system increases EGR flow during high load operation and decreases during low load operation. There is no EGR operation at idle or wide open throttle because vacuum level is low.
Single EGR Valve
The single EGR valve system is not used on Federal Montero.
Dual EGR Valve
Federal Montero models are equipped with dual EGR valve systems. It consists of primary and secondary valves controlled by carburetor vacuum. Carburetor vacuum is governed by throttle openings. The primary valve controls EGR flow at small throttle openings. The secondary valve controls EGR flow at large throttle openings.
Sub EGR Control Valve
This mechanically controlled valve is linked to the throttle valve. It controls EGR flow by responding directly to throttle valve position.
THERMO VALVE
The Thermo valve senses engine coolant temperature which prevents EGR operation below preset values. When engine warms, thermo valve opens, supplying vacuum to the EGR valve. At temperatures below 131°F (55°C) thermo valve is open and vacuum is vented so no vacuum is supplied to the EGR valve. At temperatures above 131°F (55°C) the thermo valve closes and normal EGR operation takes place.
SUB-EGR VALVE
Operate sub EGR valve manually. Valve should move smoothly through full range of motion. If operation is difficult, remove and inspect for deposits. Before removing a sub EGR valve that is difficult to operate, spray with solvent from the outside with rubber boot removed, then remove valve. If necessary, clean valve with solvent. Apply a light coat of oil. If operation remains difficult after cleaning, replace sub EGR valve.
EGR System (Montero). Scheme 6
Typical EGR Control Valve Configurations. Scheme 7
MONTERO
- Check hoses for correct routing and condition. Cold start engine and run at idle. Observe the secondary EGR valve for operation as engine speed is increased to 2500 RPM. There should be NO secondary EGR operation after cold start. If secondary EGR valve operates, replace thermo valve.
- Warm engine until coolant reaches 131°F (55°C). Increase engine speed to 2500 RPM. Observe the secondary EGR valve. The secondary EGR valve should operate. If secondary EGR valve is inoperative, check EGR valve and thermo valve. Replace as necessary.
- Detach Green-striped hose from thermo valve. Connect vacuum pump and apply vacuum. If no vacuum is available, valve is okay.
- Disconnect Green-striped hose from fitting at carburetor and connect vacuum pump to hose end. Apply 5.9 in. Hg vacuum while opening sub EGR valve by hand.
- If idle speed becomes unstable, secondary EGR valve is okay. If idling speed remains stable, valve is NOT okay. Replace EGR valve as necessary.