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Fox car engine fault lamp lighting one case

Failure phenomenon: a 2008 annual Ford Focus 1.8 L sedan with automatic transmission, mileage 42600 km. It says users, engine failure during running lamp is lit, the vehicle is running but not paresthesia.

Check Analysis: IDS fault diagnostic trouble code retrieval, display too lean mixture. The car using the intake air metering an intake pressure sensor, analyze the cause too lean mixture mainly comprises: an oil passage problems (including fuel, and a fuel injection pump, etc.), MAP sensor failure, an oxygen sensor fault, the power system control unit PCM and a control circuit failure or malfunction coke combustor and the like. Check vehicle maintenance records, done engine deep decarbonization a month ago, the whole car oil washing, cleaning air intake system and catalytic converters to clean, so you can rule out the possibility of coke. Road test, the vehicle is running normally, indicating the likelihood of oil in question is relatively small. The removable memory KAM value cleared to restart the engine after entering the closed-loop mode of operation the oxygen sensor has been at a low voltage so that the short-term correction SHRTFT fuel injection has been increasing, reaches a maximum value when the correction SHRTFT, long-term correction LONGFT He began correcting the basic fuel injection quantity, in order to achieve precise injection control. SHRTFT and LONGFT after clearing KAM KAM be able to re-learn the value of work based on the current situation, which indicates that PCM and control lines are not a problem. The oxygen sensor will not be caused by contamination of the oxygen sensor response speed is too low, so that the PCM signal it receives an error? Replacement of the oxygen sensor, air-fuel mixture is too thin display. Above exclude possible fault factors, the point of failure are mainly concentrated in the MAP sensor.

BRIEF

with IDS read data stream (figures) can be seen BARO pressure (atmospheric pressure) lower than normal levels normal should be around 101 kPa, and the secondary read data stream have shown different atmospheric pressure. Could it be that the MAP sensor measurement deviation measurement error caused by the intake of it? After replacing the MAP sensor, test the problem still exists. Because before have ruled out other possible faults, only the fuel quality is the biggest doubt.

Solution: Replace the original car gasoline tank and cleanAfter clearing KAM value, SHRTFT and LONGFT back to normal. Follow-up visits to determine the fault is no longer present.

(Lvyun Hui)

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