Mileage over 210,000 km of the 2010 Toyota Coaster bus. Users reflect: The car accelerated weakness, engine fault lights.
Inspection and analysis: maintenance personnel to detect the engine control unit, found fault code P0171- mixture too lean. The engine control unit according to engine speed, air flow rate, inlet pressure to determine the basic fuel injection time, and the air-fuel ratio sensor according to the value of the basic fuel injection time is corrected, so that the mixture control in the theoretical air-fuel ratio 14.7: 1 nearby. This will not only make the engine performance has been played, but also optimize
ELM327 Bluetooth scanner the transformation of the role of the mass of the TWC. When the mixture is too lean, the engine control unit will increase the amount of fuel injection, if the increase in the fuel injection quantity more than 35%, there will be trouble code P0171.
According to the principle of determination, the fault position may have an intake system, exhaust system, injector, fuel system, the engine control unit and the air-fuel ratio sensors. View freeze frame data records the fault code, the speed of 41 km / h, the engine speed 1 604 r / min, air flow will be 22.5, atmospheric pressure 71 kPa, coolant temperature 840C, air-fuel ratio sensor signal is 3.18 V, 0.8 V after the oxygen sensor signal short term fuel trim 17.9%, 25% long-term fuel trim. 38.2% of the total fuel trim, unusual.
Replace the air flow meter, the fault persists. The intake system inspection, found no significant leakage of the place. Remove the throttle check seals well. Inspect the exhaust system, fuel supply systems, engine cooling systems, PVC valves and connecting hoses failed to find the problem. Initiative on the air-fuel ratio test, the mixture enriched 12.5%, 12.5% reduction, test results showed normal air-fuel ratio sensor and oxygen sensor. For four injectors cleaned, refitted test
BMW V1.4.0 OBD II scanner failure remains. Check the canister and the canister solenoid valve, were normal. Replace the engine control unit, the fault persists.
Again check the intake system, or could not find the leak site, but accidentally discovered a new air filter is replaced by an unknown brand, the original problem here.
Troubleshooting: After replacing the air filter brand, data flow returned to normal. Short-term fuel trim is about 0.7%, long-term fuel trim is about 3.9%, 6.2% of the total fuel trim. Atmospheric pressure is 101 kPa, troubleshooting.
