In order to provide the best possible combination of drivability, fuel economy and emission control, the ECM/PCM uses a closed loop air/fuel metering system. The ECM/PCM monitors the HO2S signal voltage and adjusts fuel delivery based it in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The ECM/PCM will add fuel when the HO2S signal is indicating a lean condition.
Additional fuel is indicated by fuel trim values that are above 0%. The ECM/PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition.
If the revised air-fuel-ratio at idle is higher than specified value, ECM/PCM recognizes it as a fault and sends P2187.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Check the revised air-fuel-ratio at idle | 1. Air leakage 2. Improper fuel pressure 3. PCV valve stuck 4. Clogging of injector |
Enable Conditions |
•
5.8% < torque < 23%
•
Engine speed > 500rpm
•
ECT > 80℃
•
IAT < 80℃
•
Fuel System Status Closed loop | |
Threshold Value |
•
Air mass correction value of additive fuel adaption range > 5.53% | |
Diagnostic Time |
•
30 sec | |
MIL ON Condition |
•
3 driving cycles |
