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Join Date: Jun 2009
Posts: 745
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About to readjust CO can i use a afr tool?
Hi guys getting mixed responses from my web search . I need to adjust my CC to 3%
Can i use a afr tool to do it using the conversion tables on the net? Was told the numbers do not really correlate . Is this true? Thanks Erick |
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Join Date: Jul 2003
Location: Back in B'ham, AL
Posts: 3,459
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Unusual inquiry having 374 posts in Pelican... lots of info in the turbo forum. Do a search here and you'll be amaze of the results.
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Miguel woke up on the wrong side of the bed today
![]() ![]() but he's right do a search.. I do remember someone publishing a AFR to CO conversion chart ..
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"Todd" 98 Tahoe ,2007 Saturn Vue 86 930 black and stock, 80 930 blue tracdog 91 Spec Miata (yeah I race a chick car) "life"ll kill ya" Warren Zevon |
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Join Date: Jul 2008
Location: Central Washington State
Posts: 4,398
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Adjusting to 3% is all fine and dandy, but if you're trying to pass an emissions test then that will be way too rich. It's not a "magic number", but rather dependent upon your car's build and general state of tune as to how well it will idle at 3%. Lacking any hard data (such as an emissions exhaust sniffer or an AFR gauge) then let your ear tell you how she's idling as you adjust the mixture screw.
I idle at about 13.8 to 14.0 which my car seems to like. Been a long time and many adjustments since I "sniffed" with my old Gunson Gas Tester, but I seem to remember something in the neighborhood of 2.0 to 2.5% CO works well for my car.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, B&B intercooler, stock 3LDZ. |
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Registered
Join Date: Jul 2008
Location: Central Washington State
Posts: 4,398
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Adjusting to 3% is all fine and dandy, but if you're trying to pass an emissions test then that will be way too rich. It's not a "magic number", but rather dependent upon your car's build and general state of tune as to how well it will idle at 3%. Lacking any hard data (such as an emissions exhaust sniffer or an AFR gauge) then let your ear tell you how she's idling as you adjust the mixture screw.
I idle at about 13.8 to 14.0 which my car seems to like. Been a long time and many adjustments since I "sniffed" with my old Gunson Gas Tester, but I seem to remember something in the neighborhood of 2.0 to 2.5% CO works well for my car.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, B&B intercooler, stock 3LDZ. |
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Crotchety Old Bastard
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3%CO is a sweet spot for performance but can vary. Typically 13.5:AFR at idle is the same sweet spot.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8 |
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Here is the table
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Trond R. 1979 930: Garret GT35r turbo, EFI, carerra intake, Link EMS, custom GT2 cams, 98mm JE P/C, 964 crank (stroker), custom valves & ported (XtremeCylinderHeads) etc..etc.. 1972 914-6 GT replica project 1986 944 Turbo |
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Quote:
Will setting your co level to 3% ish area affect WUR operation at higher boost levels. I only ask thinking that my WUR is in need of a rebuild because of the low AFR readings I'm getting at WOT(mid 9's). I'm not sure of the correlation between having the CO level set rich and the operation of the WUR under boost at WOT. I hope I don't sound like a dumba$$ but is the effect of setting the CO level high to have the car running a little richer under higher boost pressure? Would this be something you do even with an adjustable WUR? Chris |
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