406oc.co.uk

i have 406 D9 executive (RFN) and failed emission test. result as follows
at 2500 rpm CO = 3.3 % (v/v)
HC = 320 ppm

at 800 rpm CO = 3.1% (v/v)
HC = 290 ppm

i checked the oxygen sensor outputs using oscilloscope and it shows upper stream sensor values lay around 30 mV and lower stream sensor values around 900- 1000 mV (showing rich mixture). So i replaced upper stream sensor and observe both sensor outputs are lay around 900- 1000 mV. emission test 2 results were same as before.
anybody has an idea what should i check next?
your suggestions are welcome.

ipubudu wrote:i have 406 D9 executive (RFN) and failed emission test. result as follows
at 2500 rpm CO = 3.3 % (v/v)
HC = 320 ppm

at 800 rpm CO = 3.1% (v/v)
HC = 290 ppm

i checked the oxygen sensor outputs using oscilloscope and it shows upper stream sensor values lay around 30 mV and lower stream sensor values around 900- 1000 mV (showing rich mixture). So i replaced upper stream sensor and observe both sensor outputs are lay around 900- 1000 mV. emission test 2 results were same as before.
anybody has an idea what should i check next?
your suggestions are welcome.

Italian tune-up ?

Or a bottle of Cataclean or another stuff... think its called Fortis (trade only, but usually some around ebay )

hello,
thanks for reply, i did tune up & replace new spark plugs. but result is same.