2soops Posted March 21, 2011 Share Posted March 21, 2011 Hi All, Could do with a bit of advice regarding changing my O2 sensor. When i first got my car it was a J spec TT auto, and used to return about 28 - 29 mpg, that was 7 years ago mind. Since then i have converted it to manual with a V160, and have a Super Dragger, 2nd decat and performance air filter. I tested it over a 1000 miles recently and am now getting only 23.5 mpg. Having read a lot on here about how O2 sensors are service items, and with my MOT coming up i thought i'd bite the bullet and buy a new one. I just back from my MOT man, and the emmisions test was passed with flying colours. The readings on the fast idle test were, 0.119% for CO, 26 for HC, 1.010 for Lambda and the natural idle CO was 0.125%. I am now wondering if i need to fit the new sensor as all the above tests were done with the old one in. The engine runs pretty sweet, however occaisionally it does tick over fast even when warm, and the revs dont drop very quickly between gear changes. Can anyone tell me whether i would benefit from changing it, or what could be causing the reduced mpg. The 23.5mpg was done on only normal driving with the occaisional blast, i can only imagine what i would get if i thrashed it all the time. Quote Link to comment Share on other sites More sharing options...
mellonman Posted March 21, 2011 Share Posted March 21, 2011 check the voltage that you get back from the sensor to tell if its dead. http://www.mkivsupra.net/vbb/showthread.php?35940-Narrowband-O2-Sensor&highlight=sensor Quote Link to comment Share on other sites More sharing options...
2soops Posted March 21, 2011 Author Share Posted March 21, 2011 Thanks for that, looks pretty straight forward. Quote Link to comment Share on other sites More sharing options...
pezzler Posted March 21, 2011 Share Posted March 21, 2011 I only see about 24 mpg on mine at BPU level, are you sure that the mpg's have dropped accordingly due to the increase in performance? Would the car not fail emissions or even edge towards borderline failure if the O2 was buggered? Quote Link to comment Share on other sites More sharing options...
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