07-18-2009, 09:18 PM
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#1
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GL Member
Join Date: Jul 2008
Location: Butler, PA
Posts: 633
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Air to fuel ratio
I was in a friends Niissan Sentra SE R Spec-v the other day. He had a wide band O2 sensor installed and a little screen with the readout and a knob on it. He said that he could adjust his A/F ratio by turning the knob. Now I know just enough to know what all that means, but will that actually help anything. Besides from not knowing what you're doing, I know that running too lean or too rich would be a bad thing. Anyone have any experience with these things? I'm assuming the unit with the knob just changes the resistance values that the O2 sensor sends to the ECU, thereby changing the A/F ratio. He doesn't have a turbo or anything, but it is cammed rather mildly.
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*TOTALED* - 2000 Olds Alero Sedan - 3.4L 3400 V6 - WAI - Sony Head Unit -
NEW RIDE - 2005 Buick LaCrosse - 3.8L 3800 Series III V6 - WAI - Muffler/Resonator removed -
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07-18-2009, 10:57 PM
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#2
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GLS member
Join Date: Sep 2008
Location: The Dotte of Michigan
Posts: 1,145
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I would imagine with mild cams, ajusting the A/F ratio would be usefull depending on how you plan on driving.
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1999, RED Alero GX
Mods: WAI/CAI Intake w/ K&N Filter, Dynomax Muffler, B&M Shift+ Drag DR-9 Wheels, Yokohama YK520 Tires
Soon to come: Full 2.5'' Exhaust, Re-Worked CAI Utilizing Factory Air Box, AAS Body Kit, KYB Struts, Sprint Springs
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07-19-2009, 12:21 AM
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#3
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Jack-Wagon
Join Date: Mar 2005
Location: Houston, TX
Posts: 3,834
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generally speaking unless it's a fully programmable system in a tiny little package, it may be able to change the reading the O2 sends to the computer, but the bigger question is, does it do so in a progressive manner? In order to properly tune, there are different O2 values that need to be addressed based on air flow, not on a singular adjustment across the band in a linear manner. Proper tuning is done based off MAP readings, so you can add a litttle fuel under low load, and add a lot of fuel under high load, if you see what I mean. It would be more helpful to know what model WBO2 system he's using to better explain what it's doing. Some have a knob on it that's just for changing what is displayed, rather than for adding or detracting fuel.
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07-19-2009, 12:27 AM
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#4
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636 whp
Join Date: Aug 2006
Location: AZ
Posts: 11,893
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Proper tuning is based off air-fuel ratio percent error in a MAP vs. RPM table, at least with the speed density setup on mine.
As BJ said, there's no overall adjustment, it's very specific, very individual for each condition the engine runs. Sounds kinda funny he has a magic knob to adjust the air-fuel ratio real time.
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07-19-2009, 12:51 AM
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#5
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2Screwy
Join Date: Dec 2003
Location: South Dakota
Posts: 13,238
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maybe he gets in his car and as he is WOT he adjust the knob.....
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07-19-2009, 12:38 PM
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#6
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Gone but not forgotten
Join Date: May 2008
Location: Lancaster, CA
Posts: 1,254
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why do you want to adjust it?.....Im tuned at a safe A/F ratio...I dont think there is a need to adjust some more...unless you want to push it to the limit =S
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00' Alero Coupe - Baby is wearing: Custom CAI, Pacesetter headers, custom 2.5" exhaust, 62mm TB, MP45 s/c, B&M ShiftPlus, 6500K HID, KYB-GR2, Eibach springs, R1 Concepts drilled/slotted rotors
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07-19-2009, 04:17 PM
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#7
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Boost Guru
Join Date: Mar 2004
Location: Buffalo, NY
Posts: 1,837
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Quote:
Originally Posted by [ion] C2
As BJ said, there's no overall adjustment, it's very specific, very individual for each condition the engine runs. Sounds kinda funny he has a magic knob to adjust the air-fuel ratio real time.
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I agree. I don't buy this "magic knob that he can turn to adjust A/F ratio on the fly". You should ask him what exactly he is using.
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07-19-2009, 04:50 PM
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#8
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Gone
Join Date: Mar 2004
Location: Lockport Ny
Posts: 19,244
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the makers just installed a rheostat on the sensor, as it meets the readout. So as you turn it, its adjusting the readout... but nothing else.
turn knob = moar powerz!
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07-19-2009, 11:24 PM
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#9
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Gone but not forgotten
Join Date: May 2008
Location: Lancaster, CA
Posts: 1,254
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__________________
00' Alero Coupe - Baby is wearing: Custom CAI, Pacesetter headers, custom 2.5" exhaust, 62mm TB, MP45 s/c, B&M ShiftPlus, 6500K HID, KYB-GR2, Eibach springs, R1 Concepts drilled/slotted rotors
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07-20-2009, 12:27 AM
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#10
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A-mod Pirate
Join Date: Jul 2008
Location: Big Bad Cali
Posts: 3,016
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ahahahaha^^^
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07-21-2009, 11:01 AM
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#11
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GL Member
Join Date: Jul 2008
Location: Butler, PA
Posts: 633
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Next time I see him I'll have to ask. I didn't really feel any time of difference when he adjusted it, but then again, I wasn't driving either.
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*TOTALED* - 2000 Olds Alero Sedan - 3.4L 3400 V6 - WAI - Sony Head Unit -
NEW RIDE - 2005 Buick LaCrosse - 3.8L 3800 Series III V6 - WAI - Muffler/Resonator removed -
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