- Alfa Romeo 146 2.0 Twin spark 1999 - Erratic ide, possible lambda fault Archived Message
- Alfa Romeo 146 2.0 Twin spark 1999 - Erratic ide, possible lambda fault - Peter Holland October 28, 2006, 11:21 am
- fixed - Peter Holland November 2, 2006, 7:23 am
Posted by Peter Holland on October 28, 2006, 11:21 am
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Customer complaining of erratic idle speed. Checked out DTC's and live data. Code PO170 mixture control recorded. Lambda voltage on live data sticks at around 400mV, scoping the sensor shows its actual voltage to be around 680mV and it doesn't switch. If I rev the engine for around a minute and release the throttle it will switch for about 30 seconds and then return to around 600mV. When it is switching, the ECU shows voltage dropping to a minus figure. If I earth the signal wire the live data shows a voltage of -0.26V . ECU and lambda earths check ok. Readings as follows. Co 1.12% HC 186ppm Co2 13.8% 02 0.64% Lambda 0.99 Airflow 9.6 Kg/h MAF volts 1.39 Vehicle is fitted with Bosch Motronic 1.5.5 - ECU on top of throttle body. I've tried replacing the lambda sensor with an NGK item and it behaves exactly the same. The idle speed does vary, but I've put this down to the ECU trying to correct the fueling. The vehicle drives well, the only fault is the idle speed and it doesn't stall. The management light remains off. (I think I would live with it if it was mine) |
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