Plumbs Posted December 12, 2022 Share Posted December 12, 2022 (edited) Hi all , I think my o2 sensor has died . Ok so below is two data logs one down earlier this year and one just done now . So the one done earlier this year , at idle is logging as it should near 1 lambda . Now logged it tonight and the final lambda at idle is .81 !! But it’s showing 14.2 to 15.2 on the af gauge . It’s hard to start when it’s hot and I had to give it a little throttle which Is indicating a rich condition on start up “This is my Territory by the way .” It’s also running quite rich at open loop at 100 km’s showing 12 lts per 100 km’s and 14.3 to 15.1 .which has just started doing that . I’ve changed the low slope and leaned it out which made a little bit of difference. But the tune shouldn’t change. The low slope is the same as in the log taken earlier in the year showing near 1 lambda . So a dead o2 sensor ( original o2 sensor 2005 origin) would do this ? Also stalls in reverse if you accidentally punch the throttle. regards Graham. Edited December 12, 2022 by Plumbs Quote Link to comment Share on other sites More sharing options...
hjtrbo Posted December 12, 2022 Share Posted December 12, 2022 Presuming you mean closed loop? You'll get a DTC if the O2 sensor has died. Stuck rich or lean from memory. The O2 switching volts in closed loop looks something like this when all is well (V8, not a Barra but same same)... 1 Quote Link to comment Share on other sites More sharing options...
Plumbs Posted December 12, 2022 Author Share Posted December 12, 2022 Hi thanks , sorry for my ignorance. This is in open loop ! Why is final lambda.81 in open loop ? So o2 sensor only comes into it on closed loop Eg under boost ? Quote Link to comment Share on other sites More sharing options...
hjtrbo Posted December 12, 2022 Share Posted December 12, 2022 Its coming from your commanded fuel table. A normal O2 sensor can't read anything other that stoich (lambda 1). The O2 sensor is only used for closed loop fuel corrections. Quote Link to comment Share on other sites More sharing options...
Plumbs Posted December 12, 2022 Author Share Posted December 12, 2022 (edited) Ok I’m commanding 1 at idle and in the usual fields . So something weird is going on ! I’ll reload the tune and see ? It did do a funny on me a couple of weeks ago . Car was warm and just sitting in the car park . I started it up and all was fine . Started driving and got into about 3-4 psi boost for about 2 seconds. Then the Etc light stayed on and it went into limp mode with the throttle. Then started running at 22:1 and misfiring. I pulled over , well had too , had no torque . Well I shut it done . Reset the ignition and away it went again . Seems to forgotten part of its tune ? any ideas ? Edited December 12, 2022 by Plumbs Quote Link to comment Share on other sites More sharing options...
hjtrbo Posted December 12, 2022 Share Posted December 12, 2022 Put back in a good known tune. Forscan DTC read. Go from there. Quote Link to comment Share on other sites More sharing options...
Plumbs Posted December 12, 2022 Author Share Posted December 12, 2022 Ok thanks 😊 shall try ! Quote Link to comment Share on other sites More sharing options...
Plumbs Posted December 12, 2022 Author Share Posted December 12, 2022 Ok , did what you said and it’s fixed ! Thanks! ps my thoughts are with the families of the police officers tonight. 1 Quote Link to comment Share on other sites More sharing options...
dat111 Posted December 12, 2022 Share Posted December 12, 2022 7 hours ago, Plumbs said: Ok , did what you said and it’s fixed ! Thanks! ps my thoughts are with the families of the police officers tonight. whats with the 5psi at idle man? Quote Link to comment Share on other sites More sharing options...
Plumbs Posted December 12, 2022 Author Share Posted December 12, 2022 4 minutes ago, dat111 said: whats with the 5psi at idle man? It’s in vacuum . Boost is above atmospheric or 15 psi . So - 10 psi . Cheers . Quote Link to comment Share on other sites More sharing options...
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