2. The system is installed on 4-cylinder engines of cars made in 1987-88. and on V6 engines since 1987. The system is controlled by the processor unit ECU, which is part of the vehicle's ECCS processor system. The recirculation valve is open when starting the engine, on a cold engine, at speeds above 3200 min-1.
Checking the recirculation valve
3. Find a valve (photo).
3.3 The recirculation valve on V6 engines is mounted behind the throttle body on the intake manifold RPM or below 900 RPM. Otherwise, the valve is closed.
4. Check the freedom of movement of the diaphragm by pushing it up (photo). If the diaphragm is stuck, replace the valve.
3.4 Checking the recirculation valve diaphragm
5. Start the engine and close the valve by hand by pushing the diaphragm (put on gloves). The engine should lose speed and even stall. If the engine speed does not change, then check the condition of the exhaust pipe. If a non-return valve is provided, eliminate it by connecting the damper valve and the recirculation valve with a hose. Warm up the engine and bring the speed to 2000-2500 rpm. Disconnect the vacuum hose from the recirculation valve, the diaphragm should slowly move down as the speed increases. Connect the hose, as the speed decreases, the diaphragm should slowly move down.
6. If the diaphragm does not move, then check the vacuum on the valve. To do this, disconnect the vacuum hose, which should feel underpressure. If vacuum is present, replace recirculation valve. Otherwise, check the condition of the hose, the serviceability of the damper valve.
Checking the control differential pneumatic valve (VRT valve)
7. Disconnect the vacuum hoses at the top of the valve.
8. Remove the valve. Plug one of the fittings and try to create a vacuum through the other fitting, if the vacuum can be created, then the valve is faulty (air must flow freely in the direction of suction). Pressurize the nipple at the bottom of the valve, ensuring that no air passes through the vacuum nipple. Otherwise, replace the valve. Blow out the hoses before installing the valve.
Checking the vacuum control valve (TVV valve)
Attention! On 4-cylinder injection engines, the control valve is mounted in front of the intake manifold.
9. With a cold engine, disconnect the vacuum hose at the recirculation valve, start the engine and check for vacuum buildup. If the vacuum builds up immediately, replace the TW valve. If there is no vacuum on a warm engine, check the condition of the hoses. If the hoses are OK, replace the TW valve.
Check damper valve
10. Remove the valve and blow through from the connection side with the recirculation valve, the air must pass freely. In the opposite direction, the air should pass with difficulty. Otherwise, replace the valve.
Recirculation Shutoff Solenoid Valve Test
11. Performed in a car service, as special verified equipment is required.
Control differential pneumatic valve (VRT valve)
12. Disconnect hoses, turn away screws and lift the valve.
13. Disconnect the tube at the bottom of the valve and remove the valve.
14. Installation is carried out in the reverse order.
Vacuum distributor (TW)
15. Drain about 1 liter of coolant.
16. Designate and disconnect vacuum hoses.
17. Turn out the distributor.
18. Installation is carried out in the reverse order. Wrap the distributor on hermetic.