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91LS1S10
November 12th, 2006, 06:55 PM
After doing the autove, what is considered acceptable difference from commanded and actual afr?

Rey
TAQuickness
November 12th, 2006, 10:07 PM
You'd like to get within +- 0.02 with the BEN Factors. If looking at LTFT's, you'd like everthing to be between -4 and 0.
Whippled 496
November 13th, 2006, 02:40 AM
I dont mean to hijack here because i think this is some what in line with this topic but what would be a contributing factor to extremely high LTFT's? Before I installed my intercooler this weekend, my LTFTs at idle were between 12 and 15 :eek:, and between 0 and +5 when cruising. After i installed my intercooler they average between -3.8 to -0.3 at cruise and idle now. Could high IATs contribute to high LTFT's? Or is it just a case of having a small leak after the MAF that i must have inadvertantly fixed when taking apart and putting back together the intake tubing when installing the intercooler?
91LS1S10
November 13th, 2006, 05:53 AM
My BEN factors where reading mostly +- 0.01, but checking the AFR after driving in close loop. It swings +- 1. LTFT was at +2 on the high side and -3 on the low side. Should I let it go and just tune the MAF?

Rey
TAQuickness
November 13th, 2006, 06:25 AM
Whippled - Without any additional details, it sounds like you fixed a leak.

91 - I would set the car up for CLSD, and tweak the VE table with the trims, then re-enable the MAF and tweak the MAF with the trims.
91LS1S10
November 13th, 2006, 04:49 PM
TA- Thanks for your help.

Rey
SSpdDmon
November 14th, 2006, 06:59 AM
I dont mean to hijack here because i think this is some what in line with this topic but what would be a contributing factor to extremely high LTFT's? Before I installed my intercooler this weekend, my LTFTs at idle were between 12 and 15 :eek:, and between 0 and +5 when cruising. After i installed my intercooler they average between -3.8 to -0.3 at cruise and idle now. Could high IATs contribute to high LTFT's? Or is it just a case of having a small leak after the MAF that i must have inadvertantly fixed when taking apart and putting back together the intake tubing when installing the intercooler?

It's funny...I think it's an issue that lies within the stock PCM OS. I think {B4901} was the attempt at fixing the issue. Right now, my car idles with -1.6% fuel trims with the IAT's at ~50*F. During the summer when the IAT's get up over 120*F, the fuel trims shoot up a bit. Every time I ask about the {B4901} table, people tell me to use a custom OS and 'fuggetaboudit.'