Idle Mixture Inspection / Adjustment (Vehicle without Heated Oxygen Sensor)
All vehicles not equipped with heated oxygen sensor are shipped with their CO% factory adjusted as follows.
Engine idle mixture (CO%)
0.5 – 1.5% at specified idle speed
Idle mixture adjustment should never be changed from the original factory setting. However, if during diagnosis, the check indicates idle mixture to be the cause of a driver performance complaint or emission failure, the idle mixture can be adjusted using the following procedures.
For this inspection and adjustment, exhaust gas tester (CO meter) and engine tachometer are necessary.
2) Using exhaust gas tester, check that idle mixture CO% is within above specification. If it is out of specification, adjust it to specification by turning resistor knob.
CO adjusting resistor knob to “A” increases CO% (A/F mixture becomes rich) and turning it to “B” decreases CO% (A/F mixture becomes lean).
1. CO adjusting resistor
3) If idle mixture has been adjusted, confirm that idle speed is within specification.