На 9.4. System of recirculation (EGR system)
1. It is intended for decrease in content of oxides of nitrogen in exhaust gases due to decrease in temperature of combustion of gas mixture. It is reached by redirection of a part of these gases via the recirculation valve in the soaking-up collector. The design of the valve depends on type of transmission and the expected car service conditions in this region. The refusal of this system influences operation of the engine, causing unstable work idling and at small speeds of the movement, "failures" at dispersals. The system consists of the valve of recirculation and valves operating it (or pneumatic distributors). On a part of cars the differential valve (Vrtklapan) operates operation of the valve of recirculation.
2. The system is installed on 4 cylinder engines of cars 198788 and on V6 engines since 1987. The processor ECU block which is a part of the processor ECCS system of the car operates work of system. The valve of recirculation is open at launch of the engine, on the cold engine, on turns higher than 3200
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3.3 The recirculation valve on VS engines is mounted behind the case of a butterfly valve on the soaking-up collector of rpm or it is lower than 900 rpm. In other conditions the valve is closed.
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Recirculation valve check
3. Find the valve (photo).
4. Check freedom of movement of a diaphragm, having given it (photo) up. When jamming a diaphragm replace the valve.
5. Start the engine and close the valve by hand, having pressed on a diaphragm (put on gloves). The engine has to lose turns and even to decay. If turns of the engine do not change, then check a condition of a tube of selection of exhaust gases. If the backpressure valve is provided, then exclude it, having connected a hose the damping valve and the valve of recirculation. Warm up the engine and finish turns to 20002500 about / min. Disconnect a vacuum hose from the recirculation valve, the diaphragm has to be displaced slowly down a measure of increase of turns. Attach a hose, in process of decrease in turns the diaphragm has to be displaced slowly down.
6. If the diaphragm does not move, then check depression on the valve. For this purpose disconnect a vacuum hose on which depression has to be felt. If depression is present, then replace the recirculation valve. Otherwise check a condition of a hose, serviceability of the damping valve.
Check of a control differential pneumatic valve (valve VRT)
7. Disconnect vacuum hoses in the top part of the valve.
8. Remove the valve. Muffle one of unions and try to create depression via other union if depression manages to be created, then the valve is faulty (air has to pass freely in the direction of a suction). Create pressure on the union in the lower part of the valve, at the same time air should not pass through the vacuum union. Otherwise replace the valve. Before installation of the valve blow hoses.
Check of the vacuum distributive valve (valve TVV)
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Attention! On 4 cylinder injector engines the distributive valve is mounted
in a forward part of the soaking-up collector.
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9. On the cold engine disconnect a vacuum hose on the recirculation valve, start the engine and check depression increase. If depression accrues immediately, then replace the TW valve. If on the heated-up engine depression is absent, then check a condition of hoses. If hoses are serviceable, then replace the TW valve.
Check of the damping valve
10. Remove the valve and blow from connection with the recirculation valve, air has to pass freely. Air has to pass in an opposite direction hardly. Otherwise replace the valve.
Check of the gate-type solenoidal valve of recirculation
11. It is carried out in service of car service as the special confided equipment is required.
Replacement
Control differential pneumatic valve (Vrtklapan)
12. Disconnect hoses, unscrew screws and raise the valve.
13. Disconnect a tube in the lower part of the valve and remove the valve.
14. Installation is carried out upside-down.
Vacuum distributor (TW)
15. Merge about 1 l of cooling liquid.
16. Designate and disconnect vacuum hoses.
17. Turn out the distributor.
18. Installation is carried out upside-down. Wrap the distributor on sealant.