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Thread: Rich/Lean Idle

  1. 05-07-2007 #1
    mikeyv
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    Rich/Lean Idle

    My ltrims say -10 at idle but my wb says 14.7-15.2. When I come to a stop the wb reads anywhere from 12.9-13.8 then steadily goes back to stoich. Why does it do this? I've leaned out my idle cells in the ve table a lot-low
    30's, the histo. still reads -10 ltrims and my wb still acts up. I'm running CLSD to tune my ve by the way. Any ideas? I've been working on this for like a month now and i'm starting to get a little frustrated. Thanks in advance if anyone can help me out here.
    Mike
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  2. 05-08-2007 #2
    12secSS
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    To tune with the fuel trims, you need to have closed loop operational. To tune via a wideband O2 sensor, you need to disable the closed loop, fuel trims, DFCO and COT. Since you have a wideband, I would suggest you ignore your fuel trims and turn off those items I mentioned, for tuning via a wideband. What is happening is your fuel trims are trying to do their job, by maintaining the fuel around 14.62, so your wideband will read 14.7-15.2, but since your adjusting the fuel based on closed loop, it tries to remove fuel. DFCO could be kicking in and messign with your fueling. When you disable closed loop and fuel trims (as well as those others) you will see where your fuel truely is.
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  3. 05-08-2007 #3
    mikeyv
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    DFCO is disabled but if I disable closed loop, fuel trims, cot, then i'm just tuning the ve table, correct? Then once I get it nailed down do I just keep closed loop, fuel trims, DFCO disabled for good? Sorry for the questions, I just want to learn as much as possible, thanks for replies,
    Mike
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  4. 05-08-2007 #4
    12secSS
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    Yes, you would tune the VE first. I forgot to mention, you will need to set the MAF Fail to 0, in order to tune the VE properly. Then if you want the MAF to be functional as well, you can re-enable it after the VE is close. Once the VE/MAF are tuned, you can turn back on the closed loop, fuel trims, DFCO and COT (if you have cats).
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  5. 05-08-2007 #5
    mikeyv
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    Well right now the maf fail is 0, closed loop is on, DFCO is off, COT is on because of cats, fuel trims are on. I've been tuning the ve table and everything is between -4 and 0 except idle where it is -10. So basically should I turn off everything that you suggested and just start over with the ve table?
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  6. 05-08-2007 #6
    12secSS
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    Yup, pretty much since you have a wideband, it will make things go quicker and more precise. I would also advise you to reset the fuel trims before you begin, and set the OLFA table to 1.00 on the colunms above 160 degrees ... set those back to stock when you have the VE/MAF dailed in.
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