Results 1 to 3 of 3

Thread: What afr for best cruise/idle gas mileage (closed loop)

  1. #1
    Forum User verified
    Feedback Score 1 (100%)
    Join Date
    Sep 2010
    Owner Since
    1

    Posts
    1,291
    Thanks
    77
    Thanked 89 Times in 55 Posts

    What afr for best cruise/idle gas mileage (closed loop)

    So the stock ecu while in closed loop will adjust to try and maintain 14.7 afr. Since I have dual wbs on the car I was thinking about using them to simulate nbs and fake the ecu into thinking it's adjusting for 14.7 when it's really something leaner. If you are wondering, I have innovate wbs that allow you change the scale of the analog output.

    Does anyone have any experience on what afr will actually net better gas mileage?

    I've seen a chart on Jeff's site which shows a little over 16 nets better gas mileage but at the expense of higher nitrogen oxides. Looking up catalytic converts it seems that 14.7 is where it's efficiency is best so I assume that is why 14.7 is used. I uhm, don't run a cat (shhh)... So I'm not sure what's worse, producing more nitrogen oxides or more hydrocarbons...That is a different discussion of course



    What are the consequences? Yes I know I could probably just lose weight and gain more but if I attempt this and reduce weight on top then it's even more. I'm also wondering if this would allow running colder plugs without them fowling out as easy when cruise/granny driving.

    What are any other side effects? I assume overheating might be an issue?

    Thanks
    Antoni

  2. #2
    Advanced Tech? verified Feedback Score 0 i3igpete's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Posts
    948
    Thanks
    159
    Thanked 139 Times in 87 Posts
    go as lean as you can without making it hesitate. when cruising you're not burning that much gas, so exh. temps and cylinder pressures should be fine.
    Maddog Performance Engineering

  3. #3
    Forum User Not Verified
    Feedback Score 6 (100%)
    Join Date
    Sep 2010
    Owner Since
    2004

    Location
    Cape Girardeau
    Posts
    4,857
    Thanks
    368
    Thanked 297 Times in 215 Posts
    yeah the only thing you may fight with having the stock ecu trim the fuel is going up hills it is still going to be lean and may try to knock.

    If you unplug the narrowbands and use a tuning tool with wideband tracking you can avoid this by tuning based on MAP.

    Parting 6 speed
    Pampena 3.5 Stroker, GTX 2867 Gen IIs, AEM Series2, oohnoo SMIC, DN Hardpipes, FIC 1650s, Walbro 525, aermotive fpr, Dejon intake pipes, Tial Q, Koyo Rad, Samco Hoses, Stoptech 332mm fronts, HKS GT4 Coilovers, Spec 4+ LW, JDM 6 Speed, Billet shift forks, Pampena brace

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
The 3000GT/Stealth/GTO Web History Project
3000gt.com
3000GT / Stealth International WWWboard Archive
Jim's (RED3KGT) Reststop
3000GT/Stealth/GTO Information and Resources
Team 3S
3000GT / Stealth / GTO Information
daveblack.net
3000GT/Stealth/GTO Clubs and Groups
Michigan 3S
MInnesota 3S
Wisconsin 3S
Iowa, Nebraska, Kansas 3S
North California 3000GT/Stealth
United Society of 3S Owners
3000GT/Stealth/GTO Forums
3000GT/Stealth International
3000GT/Stealth/GTO Event Pages
3S National Gathering
East Coast Gathering
Upper Mid-West Gathering
Blue Ridge Gathering