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Audi WR ur-quattro and Audi 200 KG full throttle fuel enrichment

Enrichment control system - WR ur-quattro without air conditioning

Enrichment control system - WR ur-quattro without air conditioning

The ur-quattro and Audi 200 KG engine has four modes of operation:

The only air/fuel adjustment available is the 3mm Allen mixture screw between the metering head and the paddle's plenum chamber - this is adjusted at idle using a long 3mm Allen key (Audi tool P377). The WR engine has no feedback to the ECU on achieved lambda levels and no way of controlling fuel mixture in any case - mixture levels for all other spheres of engine activity are determined mechanically. The various mechanisms are:

Only the mixture screw and the system pressure regulator are adjustable. However, it is easy for the enrichment system to fail and reduce high-end performance without this being noticeable to either the driver or unwary mechanic.

Assuming that the system pressure and mixture settings are correct:

Wholesale hose replacement is usually more cost-effective than detailed debugging.

part number N 020 353 5 (5 metre length)
580 (x3)
640 (x4)
Total2.50 metres

Part number N 900 996 01 (5 metre length)
Total1.43 metres

Single ear clips can be bought from most motor factors and from larger branches of B&Q - take the hose in for them to select the right clips. T-pieces can be bought from the same place. The plastic spigots - especially on the thermopneumatic valve (24) and the solenoid valve (9) - are very fragile and it is recommended that the other end of the existing hose be detached and the component removed from car for the clip to be cut off carefully. The thermopneumatic valve is used on many Audi 100s and 200s, and will be found on the rear of the head. Only the one-way valve (18 on the diagram) is directionally sensitive - the white end connects to the solenoid valve.

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