2003 Nissan



July, 9, 2008 AT 8:37 PM

Engine Performance problem
2003 Other Nissan Models 4 cyl Two Wheel Drive Manual 40000 miles

Hi, I was hoping you could help me, I have a nissan micra (new shape) 2003 1.0ltr engine and I am getting about 20 MPG from it. The engine management light has come on so I have had the diagnostics on it and the fault codes says the engine is running lean. Somewhat surprising considering I am only getting 20 to the gallon. There is no problem starting the car and it is running reasonably well considering the fuel consumption. Plugs are coking up and there is a very strong smell of petrol. From people I have spoken to suggestions are it could possibly be the fuel pressure valve faulty or the exhaust catalyst sensors. I am told there are 2 sensors, 1 in the catalyst and the other in the block and that of the 2 it is more likely to be the 1 in the block.

1 Answer



July, 9, 2008 AT 8:50 PM

Could be an oxygen sensor/s problem not switching accordingly to meet the stoichimetric window of 14.7 to 1 ratio

A lean fuel condition can be caused by: * Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

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