JohnA Posted May 3, 2005 Share Posted May 3, 2005 How long are they supposed to live in the case of supras? Usually narrowbands are rated at 50+K miles but could it be that they live less in the case of Supras? (too high EGTs, whatever...) Judging from the poor fuel consumption most people here take for granted (even at closed-loop operation) would it be far-fetched to suspect dodgy O2 sensors? Quote Link to comment Share on other sites More sharing options...
dude Posted May 3, 2005 Share Posted May 3, 2005 Depends what fuel you run and additives John Dude Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 3, 2005 Author Share Posted May 3, 2005 Well running too rich, or running leaded fuel is a recipe to kill the sensor, I take it everyone here knows this. But I see no reason for the engine to return mpg in the 20s when it's closed-loop, that indicates a tired sensor, that shows leaner than reality. I've also seen an old theory from 'Mycroft' implying that the sensor location forces it to use contaminated air as the 'fresh air' comparison, but I'm not convinced that this is the case. Quote Link to comment Share on other sites More sharing options...
jase_93tt Posted May 4, 2005 Share Posted May 4, 2005 Actually what JohnA says may quite well be true. I recently changed the plugs on my one and noticed that the tips looked like the car was running a tad lean (bear in mind the car was completely stock at this point). So it could be the 02 sensor wearing out and leaning the mixture. Anyone ? Quote Link to comment Share on other sites More sharing options...
Dragonball Posted May 4, 2005 Share Posted May 4, 2005 We have just done two of these boys! Quote Link to comment Share on other sites More sharing options...
tbourner Posted May 4, 2005 Share Posted May 4, 2005 Changed my 50k ish one and it made no difference to anything. Quote Link to comment Share on other sites More sharing options...
dude Posted May 4, 2005 Share Posted May 4, 2005 The O2 sensor is prob the easiest thing on the car to change except channels on the radio , 2 12mm nuts and unplug it from the loom ,insert new one and bobs your uncle , even a chimp could do it !!!! Thor sell cheap O2 sensors as well. Dude Quote Link to comment Share on other sites More sharing options...
Digsy Posted May 4, 2005 Share Posted May 4, 2005 But I see no reason for the engine to return mpg in the 20s when it's closed-loop, that indicates a tired sensor, that shows leaner than reality. Strange. What do you think it should be returning, then? ...and silicone contamination will fook up an O2 sensor as well, just in case anyone has any ideas about gooping Mastik around their engine bay to seal up boost leaks Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 Strange. What do you think it should be returning, then? Top of my head, with the supra's weight and aeros and wide tyres, low 30s mate. (while poodling around in close-loop in vacuum) My Calibra turbo was doing low forties (mpg) on mild motorway runs (say constant 70-90mph coming back from TOTB) after it was freshly rebuilt. ...and silicone contamination will fook up an O2 sensor as well, just in case anyone has any ideas about gooping Mastik around their engine bay to seal up boost leaks very true, RTV-alert Also these oxygen sensors cannot be cleaned and/or refurbished, as some people seem to think. WD40 kills them as well. They slowly degrade and show leaner than they should, so the ECU tends to throw more fuel than it otherwise would have done. However, since people here report no appreciable change in fuel consumption after the oxygen sensor has been replaced, it may be something else at work... When I find time to fit my wideband I'll see how the stock fuelling is. Quote Link to comment Share on other sites More sharing options...
MrAngry Posted May 4, 2005 Share Posted May 4, 2005 The sensor is £109 + Vat from Toyota. I had a problem with running very rich at top end. which was really brought home after fitting a new walbro pump. After changing it there is a huge difference. Obviously it wasn't allowing the fuel to be trimmed correctly. Had a lot of great minds puzzled for a while. Quote Link to comment Share on other sites More sharing options...
Digsy Posted May 4, 2005 Share Posted May 4, 2005 Top of my head, with the supra's weight and aeros and wide tyres, low 30s mate. (while poodling around in close-loop in vacuum) My Calibra turbo was doing low forties (mpg) on mild motorway runs (say constant 70-90mph coming back from TOTB) after it was freshly rebuilt. My NA returns a steady 23mpg ding the daily grind. Never had it anywhere near the low 30's. Closest was a real poodle-fest sub-70 all the way trip back from when I picked up the car and I was keeping pace with my Dad in his diesel Mondeo. That returned a never-to-be-repeated 28mpg. I did think my car was running rich at one point and the O2 sensor was the prime suspect, but I had the emissions checked and my AFRs as measured at the tailpipe is spot on. I don't think I've ever had anyone say that the Supra can run in the 30's (apart from a guy trying to sell me one ) Quote Link to comment Share on other sites More sharing options...
JustGav Posted May 4, 2005 Share Posted May 4, 2005 I am replacing all of my O2 sensors while I'm building my new car, but it is purely as a precaution as well as being needed for the tuning side of things.... Gav Quote Link to comment Share on other sites More sharing options...
tbourner Posted May 4, 2005 Share Posted May 4, 2005 I wouldn't expect any 3.0l 6 cylinder car to get near 30mpg!! Quote Link to comment Share on other sites More sharing options...
MrAngry Posted May 4, 2005 Share Posted May 4, 2005 28mpg is the best I have ever managed that was last Summer. 350 miles on the motorway at around 80-90 all the way, without holdups The car was completely stock also Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 I'm looking at oxygen sensors at the moment, not keen to pay £100+ (plus vat) to Mr "T" Unfortunately my first UK choice (half price OEM lambda stuff) don't quote the Supra. But US sites do, and at $65 - $75 depending on flange or not. That's a third of rip-off UK Anyone know of a half-decent UK supplier? Quote Link to comment Share on other sites More sharing options...
JustGav Posted May 4, 2005 Share Posted May 4, 2005 Hmmm, tried lexus out of interest??? I'd be interested to see if there is a price difference between the two... Gav Quote Link to comment Share on other sites More sharing options...
JustGav Posted May 4, 2005 Share Posted May 4, 2005 Or just get a AEM UEGO which unless I am mistaken (which is more than possible) has got an narrow band output which can go directly into the ECU, and you get the best of both worlds... a dash gauge from a wideband, and the narrowband for the ECU Quote Link to comment Share on other sites More sharing options...
Alex Posted May 4, 2005 Share Posted May 4, 2005 Before replacing one try soaking it in Lemon Juice and then rinsing with Brake cleaner. I did it after mapping my car and knowing I'd been going rich...with no other system changes or resets it had to re-learn the idle when I started her up because the O2 had been clogged up and was now reading better. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 Or just get a AEM UEGO which unless I am mistaken (which is more than possible) has got an narrow band output which can go directly into the ECU, and you get the best of both worlds... a dash gauge from a wideband, and the narrowband for the ECU I've already got that mate, just haven't fitted it on the soop yet. Do you know of anyone who's done it though (just to verify that the supra sensor has standard thread)? I was thinking that maybe the wideband could be a bit downsteam, to protect it from the heat, although how those temps are affected by the lack of cats I don't know... Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 Before replacing one try soaking it in Lemon Juice and then rinsing with Brake cleaner.... I've tried to rejuvinate 02 sensors in the past with no success. Didn't try acidic bath though, maybe it cuts through the carbon deposits without damaging the rest of the sensor, but being a miniature battery I think the sensor is best replaced after 50K miles anyway... Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 4, 2005 Share Posted May 4, 2005 I suppose there is a difference between old age (replace) and coked-up (clean). -Ian Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 Well old-age wear for them is usually due to the gradual buildup of contaminants, or else they'd keep working for longer. There might be certain liquids that dissolve the crud without damaging the sensor, we just need to find which ones though... Also don't forget that these sensors are not sealed units, so the cleaning liquids will go inside too. Quote Link to comment Share on other sites More sharing options...
Keith C Posted May 4, 2005 Share Posted May 4, 2005 Ah - could a knackered o2 sensor explain my running very rich at WOT? I did once get 31mpg though. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2005 Author Share Posted May 4, 2005 I still haven't figured out what that second 'sensor' downstream does. In the US manuals it appears to be an oxygen sensor, but it looks a bit too thin to me, maybe it's a temp sensor, does anybody here knows what it really is on UK cars? If it were an o2 sensor to verify that the cat works, then surely the ECU would be throwing an error if it's decatted. Which it doesn't do. Quote Link to comment Share on other sites More sharing options...
Alex Posted May 4, 2005 Share Posted May 4, 2005 There might be certain liquids that dissolve the crud without damaging the sensor, we just need to find which ones though... We have...Lemon Juice. Cause if it didn't work my 02 would be knackered now. And it passed it's MOT with a single on so I'm guessing it's fine. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.