Idle Speed & Mixture

With engine at normal operating temperature, turn all electrical accessories off. With engine stopped, disconnect both plugs from idle stabilizer unit and connect them together. Disconnect and plug PCV valve hose.
Check and adjust ignition timing as necessary. Adjust idle speed to specified RPM using adjusting screw on side of throttle valve housing. Be sure that engine cooling fan is not running while adjustments are being made.
Remove cap from CO test receptacle on exhaust manifold and connect CO tester hose directly to test receptacle. Connect a dwell meter to frequency valve electrical connector. Zero dwell meter and set it to the 4-cylinder scale.
On California models, turn off all electrical sources. On Federal models, turn on the headlight high beams. Disconnect oxygen sensor wire at connector and check dwell meter reading. Race engine briefly before reading meter. Meter reading must be a constant 40-50°.
Adjust CO level using hex wrench. Turn adjusting tool clockwise to increase CO and counterclockwise to decrease CO. Always adjust CO level from lean to rich.
NOTE: Do not press down on adjusting tool when adjusting CO level. Do not accelerate engine with tool in place and always remove tool after each adjustment.

Reconnect oxygen sensor wire and check dwell meter reading. Meter needle should now vibrate. Reconnect hoses and idle stabilizer. Recheck idle speed.

IDLE SPEED & CO LEVEL

Application

Idle RPM

CO%

4000 & 5000

Federal

⁽¹⁾ 800-1000

0.4-1.2

Calif.

880-1000

0.4-1.2

5000 Turbo

880-1000

0.4-1.2

Quattro

790-910

0.3-1.2

⁽¹⁾	Set 5000 model to 850-1000 RPM.