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12.9. Unsteady Idle Speed after Warming up
Yes Remove the failure displayed 1 Put the ignition switch to “ON”. Use a failure diagnostic tester to check if any failure information record exists. No Next step Yes Next step 2 Turn on ignition switch, connect an adaptor between ECU and harness, and then check if the voltage between 17# and 42# pins of ECU, between 39# and 17# pins of ECU (signal output terminal of intake air temperature sensor and coolant temperature sensor) as well as 64#, 65#, 66#, 67# pins of ECU (for control of DC motor) is normal. No Repair or replace the harness
Yes Next step 3 Turn off the engine. Check the air cleaner and look if it is open. No Replace Yes Next step 4 After starting successfully, check if air intake consumption of the engine at idle speed is around 300Kg/h (remember to check if cylinder pressure is normal). No Eliminate the leakage failure of air intake system Yes Next step 5 Connect fuel manometer valve. Short 30# and 87# pins of fuel pump relay to make the fuel pump run, and then check if fuel pressure is around 400kPa. No 9 Yes 8 6 Use a special joint to directly provide a 12V power supply and intermittent ground wire from battery to injector and check if the injector can work intermittently. No Next step Yes Replace 7 Clean out the fuel injector and look if it can work correctly. No Replace fuel injector Yes Replace fuel 8 Check if fuel is deteroprated or moisture. No 14 Yes Next step 9 Check if the fuel pressure value is below 300kPa. No 13 Yes Next step 10 Close the fuel manometer valve. Re-engage the ignition switch to let the fuel pump run for a period of time, and then check if fuel pressure can be built up. No 12 Yes Replace fuel pressure regulator 11 Open the valve of fuel gauge and clamp the oil return pipe by oil return baffle so that the oil can not return. Check if the oil pressure occurs immediately. No Repair and replace fuel injector and oil pipe |