Milanski Posted June 26, 2019 Share Posted June 26, 2019 I am scratching my head (bald head!). I have notice whilst in IDLE DRIVE (not sure if it does it IDLE PARK - will check this tomorrow) I see commanded lambda pushed out to 0.9 and then the fuel trims follow. The PCM hold 0.9Lambda quite well at the idle. ECT = 94Deg Fuel Base Table is "1" Fuel Cold Base Table is 0.85 Use Fuel Base above 71Deg so it should be 1. I just picked this up this arvo and have gone through days of logs to find the same. Would anyone in the forum please point me in the right direction please. Quote Link to comment Share on other sites More sharing options...
Roland@pcmtec Posted June 27, 2019 Share Posted June 27, 2019 1.0 * 1 -1.133 = 0.867 You have 13% short term fuel trims so it makes sense to me. This is normal as the narrowband is trying to induce a rich lean lambda oscillation to keep the catalytic converter in the efficiency region. Can you log your o2 volts against it? It is probably reading lean hence the short term trim commanding a rich afr to attempt to get it to swing. Short term trims are not very useful to log as they will always oscillate. Just look at the long term trims and your actual wideband reading. The fact you have -0.8% LTFT means you've got it dialed in well imo. Quote Link to comment Share on other sites More sharing options...
Milanski Posted June 27, 2019 Author Share Posted June 27, 2019 Wow a bit more smarts. Even though I want it to be 1 the PCM will try to do as you say - richen and oscillate to keep cats efficient. Quote Link to comment Share on other sites More sharing options...
Roland@pcmtec Posted June 27, 2019 Share Posted June 27, 2019 If you want exactly 1 then you need to run open loop at all times. You can do this in a BA/BF if you follow the guide, FG you may need to unplug the sensor to achieve this. Quote Link to comment Share on other sites More sharing options...
Milanski Posted June 27, 2019 Author Share Posted June 27, 2019 definitely don't want to run Open Loop. Just curious as to the logic, makes good sense. Quote Link to comment Share on other sites More sharing options...
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