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Home >> Volvo >> 1983 >> 242 GLT, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH LH >> Adjustments >> Idle Speed & Co-Content, Checking/Adjusting

Idle Speed & Co-Content, Checking/Adjusting

NOTE: It is important that the other engine settings are correctly adjusted (e.g., timing) if valid results are to be obtained.
  1. The engine should be warm and idling. Warm up the engine at 1500 RPM. Check/adjust the CO-content approximately 5 minutes (no earlier), after the radiator thermostat has opened.
  2. Use an exhaust as extractor that fits loosely over the exhaust pipe. Excessive extraction may yield incorrect results when checking/adjusting CO-content.
  3. Check throttle valve switch adjustment. See THROTTLE VALVE SWITCH ADJUSTMENT  .
  4. Connect rev counter. Connect CO-meter by connecting meter to nipple in exhaust pipe ahead of catalytic converter.
    WARNING: Connecting nipple for CO-meter may be very hot.
  5. Start and warm engine. Check idle speed, should be 12 r/s (750 rpm). Air conditioning should be disengaged. Adjust idle speed if required. If idle speed varies excessively check that air control valve hoses are not blocked.
  6. If required, adjust idle speed. Ground test point, blue-white wire. Adjust engine speed w/idle screw to 720 RPM. If engine speed cannot be adjusted to correct value, adjust throttle valve and control. See THROTTLE VALVE below. Remove test point ground. Engine speed should increase to 750 +/- 20 RPM.
  7. Disconnect Lambda-son. Check CO-content. Check value should be 0.4-0.8 percent. Adjustment of CO-content should be made if CO-content lies outside of check value and when all other possible causes of incorrect CO-content have been checked/corrected.
  8. If required adjust CO-content. Remove adjustment seal. Turn off engine. Drill 2 holes (2 mm or 5/64 in.) in seal. Pull out plug with snap-ring pliers. Start engine. Adjust CO-content. The value should be 0.6 percent. Adjustment screw has a range of 15 turns and lacks distinct end stops. Turning counter-clockwise decreases CO-content and turning clockwise increases CO-content.
  9. To Connect/check Lambda-sond, connect. When it is connected the CO-connect should decrease.
  10. Check idle speed. Adjust if required, step 6 above.
  11. Turn off engine. Seal CO-adjustment (if adjustment was performed). Use a new plug. Tap in place.
    WARNING: Connecting nipple for CO-meter is very hot.
  12. Remove test meter and install plug.
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