pjavon Posted June 6, 2009 Share Posted June 6, 2009 Just done the test for the o2 sensors on my N/A. and had some bad results if it is correct http://www.mkivsupra.net/vbb/showthread.php?t=35940 OX1=0.1 OX2=0.05 Does this mean my O2 sensors knackered, if so anyone know the cheapest place to buy them. The thing is the car seems to run fine, i got 28mpg on my round trip to japfest(at a steady 70ish, 450 mile round trip) and it passed an MOT a month ago. What do people suggest, do the lemon trick first or is it a case of they need replacing. Thanks for any advice. Quote Link to comment Share on other sites More sharing options...
matthewm1965 Posted June 6, 2009 Share Posted June 6, 2009 A lot depends on the meter you are using to measure the signal. You should see the meter flicking up and down, the faster the better, but I have usually seen it at about once per second. You really need an osciloscope to see it properly, but not many people can afford such luxuries! Some meters will just average the signal and you will not see a true reading. Make sure the engine is fully warmed up before you measure as the engine doesn't go into closed loop control until it reaches a certain temperature. I just bought a pair of Denso/Toyota ones for my N/A from RockAuto in the states. They worked out at £101 for the pair inc shipping & tax and were delivered in less than a week. Matt Quote Link to comment Share on other sites More sharing options...
pjavon Posted June 7, 2009 Author Share Posted June 7, 2009 Thanks for your reply Matt, i was concerned as to weather i was o.k. using a normal volt meter. Quote Link to comment Share on other sites More sharing options...
matthewm1965 Posted June 7, 2009 Share Posted June 7, 2009 If its a digital meter, you should see it flicking about, not a steady reading. With the older analogue types, it all depends how damped the movement is. You sometimes have to blip the throttle to get it into closed loop mode, but it should be in this mode at idle anyway, providing it is up to temp. There cant be much wrong if you are getting 28MPG. I am only getting 21. I am hoping it will improve when I change the sensors. They are sat on the shelf in the garage waiting for my return home from working overseas. Matt Quote Link to comment Share on other sites More sharing options...
Supra-Brett Posted June 7, 2009 Share Posted June 7, 2009 If its a digital meter, you should see it flicking about, not a steady reading. With the older analogue types, it all depends how damped the movement is. You sometimes have to blip the throttle to get it into closed loop mode, but it should be in this mode at idle anyway, providing it is up to temp. There cant be much wrong if you are getting 28MPG. I am only getting 21. I am hoping it will improve when I change the sensors. They are sat on the shelf in the garage waiting for my return home from working overseas. Matt I would die for 21mpg, never mind 28mpg. I was getting 14mpg before changing my o2 sensors, now im getting 19mpg so thats a 33% increase:d. I must have a heavy right foot (edit - i do have a heavy right foot) Quote Link to comment Share on other sites More sharing options...
kaahari Posted June 7, 2009 Share Posted June 7, 2009 (edited) Hi! My jspec tt shows OX1 voltage 0.3 - 0.6 - 0.8 - 0.3 - 0.6 - 0.8... about half second each. No error codes, and engine running smoothly. Innovate wideband shows about 14.3 - 14.7. I wonder if the sensor in ok? Or bigger broblem? :blink: Edited June 7, 2009 by kaahari (see edit history) Quote Link to comment Share on other sites More sharing options...
pjavon Posted June 7, 2009 Author Share Posted June 7, 2009 I only get about 18Mpg if i'm going out for a 'drive' but on a decent run it does do high 20's It is a digital meter Matt but i had turned the car off for a couple of minutes and just started it up so maybe i should of blipped the throttle to be sure it was in closed loop mode(what ever that is:d) I'll try it again Thanks for your help Paul Quote Link to comment Share on other sites More sharing options...
matthewm1965 Posted June 7, 2009 Share Posted June 7, 2009 Hi! My jspec tt shows OX1 voltage 0.3 - 0.6 - 0.8 - 0.3 - 0.6 - 0.8... about half second each. No error codes, and engine running smoothly. Innovate wideband shows about 14.3 - 14.7. I wonder if the sensor in ok? Or bigger broblem? :blink: looks spot on. 14.7 is the ideal stoichiometric air fuel ratio, so its maybe running slightly rich. But thats beter than running lean;) Quote Link to comment Share on other sites More sharing options...
matthewm1965 Posted June 7, 2009 Share Posted June 7, 2009 I only get about 18Mpg if i'm going out for a 'drive' but on a decent run it does do high 20's It is a digital meter Matt but i had turned the car off for a couple of minutes and just started it up so maybe i should of blipped the throttle to be sure it was in closed loop mode(what ever that is:d) I'll try it again Thanks for your help Paul Closed loop mode is where the fueling is determined by the signal from the O2 sensor. It tries to maintain an air/fuel ratio of 14.7 This mode is at idle and steady cruising. It goes into open mode under acceleration, when the fueling is determined by the mapping, throttle angle, manifold pressure and probably other things but ignores the signal from the O2 sensors. http://en.wikipedia.org/wiki/Oxygen_sensor Thats my understanding of it anyway! Matt Quote Link to comment Share on other sites More sharing options...
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