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How to Check AFR?

Discussion in 'Performance and Tuning' started by WHT.RUS, Nov 24, 2014.

  1. Nov 24, 2014 at 5:38 AM
    #1
    WHT.RUS

    WHT.RUS [OP] Well-Known Member

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    Ive installed a SC with a 2.85 pulley on my truck. Ive also got the bullydog tuner and will be installing it today. Id like to check my AFR to make sure the truck is not running lean with the tuner and cause damage. How do I check th AFRs without going to a shop?
     
  2. Nov 24, 2014 at 6:37 AM
    #2
    Lurkin

    Lurkin Well-Known Member

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    Scanguage can, think maybe Ultraguage, the data is in the ECU/OBDII, can also get a wireless OBD scanner and a smartphone app. Also the tried and true, install a sensor and guage method.
     
  3. Nov 24, 2014 at 7:59 AM
    #3
    WHT.RUS

    WHT.RUS [OP] Well-Known Member

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    Thanks! What is the normal AFR for a supercharged tacoma?
     
  4. Nov 24, 2014 at 10:00 AM
    #4
    WHT.RUS

    WHT.RUS [OP] Well-Known Member

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    A dedicated wideband?
     
  5. Nov 24, 2014 at 10:09 AM
    #5
    StAndrew

    StAndrew Wait for it...

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  6. Nov 24, 2014 at 11:45 PM
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    kigmob

    kigmob Well-Known Member

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  7. Nov 24, 2014 at 11:50 PM
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    TheMuffinMan

    TheMuffinMan Banana Nut

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    AFR is not always going to be 14.7.

    It's common to see it drop under WOT and high RPM's to increase cylinder and head cooling by enriching the mixture. I've seen as low as 10.5-11 though usually not much under 12 under aggressive running on other engines (I haven't measured the taco).

    Cruising and light throttle will be 14.7 or close to it most likely.
     
  8. Nov 25, 2014 at 5:44 AM
    #8
    Lurkin

    Lurkin Well-Known Member

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    Closed loop operation should always hover around 14.7, give or take a few tenths. Open loop, as mentioned above, will richen the mix to 12.5 or so, give or take a few 1's :). Richening the mix at open loop is more of a CYA move to ensure that the engine doesn't lean itself out and start burning internal parts.
     
  9. Nov 25, 2014 at 5:58 AM
    #9
    WHT.RUS

    WHT.RUS [OP] Well-Known Member

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    So correct me if I am wrong, i just want to make sure. Anything below 14.7 is a rich mixture and is fine for the motor while anything above is a lean mix and is bad. An upgrade in the pump should be in order now since i added to sc?
     
  10. Nov 25, 2014 at 9:41 AM
    #10
    kigmob

    kigmob Well-Known Member

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    You should have a larger fuel pump as well as some form of fuel management to properly fuel the SC. And yes, in general anything below 14.7 is considered "rich" and above is considered "lean". However, with respect to boost, I look at it as anything below 12.5 or so is rich and anything above 12.5 is lean.. So what I am getting at is when you get into boost, you want the AFR to be 12.5 and lower.
     
  11. Nov 25, 2014 at 9:52 AM
    #11
    StAndrew

    StAndrew Wait for it...

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    What year is your truck? You should get the URD 7th injector kit if you have a TRD S/C. It will come with a pump.
     
  12. Dec 21, 2014 at 7:09 AM
    #12
    WHT.RUS

    WHT.RUS [OP] Well-Known Member

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    Ditched the bullydog. It was junk! Thanks for the info guys
     
  13. Dec 21, 2014 at 9:24 AM
    #13
    vssman

    vssman Rocket Engineer

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    The AEM in the link above is a great unit. I have one in my tri carb 63 falcon. If you don't want a permanent gauge, there are a few that clip on the tail pipe. Summit, Jegs, etc... have them listed with along with some more tech info on how they operate. As noted above, boosted typically run a bit richer (lower numbers) vs normally aspirated engines.
     
  14. Dec 22, 2014 at 7:38 AM
    #14
    XPOTRPR

    XPOTRPR #safetydevelopment

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    Definitely.. im still runnin rich as hell.

    this. I also recommend the AEM.
     
  15. Dec 22, 2014 at 8:03 AM
    #15
    Torspd

    Torspd Tor-nication

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    N/A, at OEM fuel pressure, stock ECU, & stock injectors, my engine was still running ~10.8:1 AFR's at WOT. OEM tune is just way to rich. That would be on the richer side for a boosted application. 12.0 - 12.5 is the optimal rich AFR for N/A. Optimal lean would be 13.0:1. For optimal boosted, F/I, 11.0 - 11.5:1. On non ethanol.
     
  16. Dec 22, 2014 at 8:18 AM
    #16
    XPOTRPR

    XPOTRPR #safetydevelopment

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    I need to check my AFR at WOT again.. once the driveshaft is fixed and I can actually get into boost :eek:
     

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