90 Quattro 20V L5-2309cc 2.3L DOHC (7A) (1990)
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Idle Speed: Adjustments
Models Produced From March 1990
Before making any adjustments to the idle speed or air/fuel ratio, observe the following conditions.
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Perform vehicle self diagnostics, make any necessary repairs (there must be no fault codes stored in memory when adjusting idle speed or
air/fuel ratio).
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Engine is at normal operating temperature.
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All electrical loads turned OFF (A/C, cooling fan, heater blower, etc.)
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Crankcase ventilation hose disconnected and plugged on manifold side.
1.
Disconnect and plug vacuum hose from carbon canister shut-off valve.
CO Adjustment Screw Anti-Tampering Cap Location (arrow)
2.
Remove cap from CO tap tube and connect emission analyzer.
3.
Start engine and idle.
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Idle speed must be 770-830 rpm (800 rpm preferred).
^
CO content must be 0.3-1.2% by volume (0.5-1.0% preferred).
If OK, no adjustment necessary.
If not OK, continue.
Diagnostic Connectors - Activating Self Diagnostics
4.
With engine idling below 2,000 rpm, connect jumper wire between diagnostic connectors (as shown in diagram) and leave connected. It is not
necessary to connect LED test light for this procedure.
With the engine idling and jumper wire installed, the ECU will:
