Idle Speed: Adjustments

Fig. 13 Curb Idle Speed Adjustment:

Fig. 14 Idle & Mixture Adjustment Screws & Connector Locations:

1. Run engine until normal operating temperature is reached, with a stabilized RPM of 3000. Allow two full cycles of clutch fan.
2. Ensure ignition system is properly adjusted, declutchable fan is released and air cleaner is clean and properly installed.
3. Ensure proper setting of throttle flap adjustment, see ``Throttle Flap Adjustment.''
4. Check and repair leaks of intake circuit.
5. Turn all electrical accessories off.
6. Adjust air-bleed screw (1) on throttle flap housing by-pass channel and the richness screw (2) on the air flow sensor, using a 5mm Allen wrench, Fig. 13.
7. Using exhaust gas analyzer and probe adapter tool No. 0141-BB and teflon hose tool No. 90-14 or equivalents, check at front of catalytic converter.
8. Disconnect wire from 22 (4), from injection ECU, Fig. 13.
9. Disconnect wires from 140°F thermocontact (1), Fig. 14, then connect together.
10. Disconnect PCV hose (2), plug end, leaving PCV fitting (3), open.
11. Measure CO concentration at front of catalytic converter. Measurement should read 1.0-1.6%. Idle speed should be 960-970 RPM on models with automatic trans., and 1010 RPM on models with manual trans.
12. On all models, if measurements are not within specifications, drill off-center into the central portion of the tamper resistant plug, located on the air flow sensor, using a 4.5mm drill, to a depth of .197 inch (5mm).
13. Thread a sheet metal screw into the hole in plug, then remove plug.
14. Adjust idle speed adjusting screw (6), then the mixture screw (7) to specifications, Fig. 13. Turn in the mixture screw to enrich the air/fuel mixture and unscrew the mixture screw to lean the air/fuel mixture. After each mixture adjustment, readjust the idle speed.
15. Reconnect the 140°F thermocontact, PCV hose, then the ECU electrical connector.