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GD(H6DO)-72 Diagnostic Trouble Code (DTC) Detecting Criteria GENERAL DESCRIPTION BA:DTC P0171 SYSTEM TOO LEAN (BANK 1) 1. OUTLINE OF DIAGNOSIS Detect fuel system malfunction by the amount of main feedback control. Diagnostic method Fuel system is diagnosed by comparing the target air fuel ratio calculated by ECM with the actual air fuel ratio 2. ENABLE CONDITION 3. GENERAL DRIVING CYCLE Perform the diagnosis continuously at idling or at a constant speed after warming up the engine. 4. DIAGNOSTIC METHOD • Abnormality Judgement Compare the diagnosed value (fsobd) with the threshold value, and if a condition meeting the malfunction cri- Time Needed for Diagnosis: 10 s × 5 time(s) • Normality Judgement Judge as OK and clear the NG if the continuous time while the following conditions are established is more Time Needed for Diagnosis: 10 s Secondary Parameters Enable Conditions A/F main learning system In operation Engine coolant temperature t 75 °C (167 °F) Engine load change < 0.02 g/rev (0 oz/rev) Engine load t Value of Map 1 Map1 Engine speed (rpm) Idling 700 1000 1500 2000 2500 3000 3500 4000 4500 5000 Measured value (g(oz)/rev) Non-turbo 0.357 (0.01) 0.25 (0.01) 0.25 (0.01) 0.317 (0.01) 0.326 (0.01) 0.337 (0.01) 0.397 (0.01) 0.439 (0.02) 0.454 (0.02) 0.454 (0.02) Judgement Value Malfunction criteria Threshold value fsobd = (sglmd – tglmda) + faf + flaf t Value of Map 2 In this case: sglmd = measured lambda
tglmda = target lambda
faf = main feedback compensation coef- flaf = main feedback learning compensa- Map2 Amount of air (g (oz)/s) 0 (0) 3.2 (0.11) 6.4 (0.23) 9.6 (0.34) 12.8 (0.45) 16 (0.56) 19.2 (0.68) fsobdL1 (%) 1.4 1.4 1.332 1.265 1.265 1.265 1.265 Judgement Value Malfunction Criteria Threshold Value fsobd = (sglmd – tglmda) + faf + flaf < 1.2 |