wide band readings ?

Discussion in 'SRT Hellcat General Discussions' started by GrndFnk, Feb 8, 2016.

  1. GrndFnk

    GrndFnk VIP Hellcat Member

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    Was wondering what guys/gals wide bands are reading when hot at idle, cruise and WOT ?
    I searched it but didn't come up with anything.
    Thanks
     
  2. Sepipr21

    Sepipr21 Silver Member

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    I don't even know what this means. I need to learn more.
     
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  3. GrndFnk

    GrndFnk VIP Hellcat Member

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    It is a great tuning tool that the Hellcat has in the exhaust and displays FA ratio on one of the pages. I forget where and cannot get at the car at the moment. It is an oxygen sensor that reads out the actual fuel air ratio. (actually a 0-5v signal that is converted) I used them on my other vehicles most recently an '09 SRT.
    Attached is an aftermarket NTK made by NGK which uses the arguably top of the line NTK sensor. I have never had a glitch or failure with the previous generation of these which was called the AFX Powerdex.
    I may get one for the Cat and install it in front of the catalytic converters to compare against what the factory wide band reads which is located farther back in the system I am told. I am not convinced the data from the factory sensor is accurate based on hearing reports of it reading in the 13's at WOT. It just doesn't make sense to me how an engine this powerful can run 13 to 1 FA ratio at WOT and live on 93 octane. My turbo cars always liked around 11.0 to 11.2 to 1 and my N/A (naturally aspirated) liked 12.5 to 1.
     

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  4. usmc341

    usmc341 Gold Member

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    My Shelby came with dual wide bands and you are correct.. 11.1 is the sweet spot for forced induction engines. At WOT stock tune showed 10-10.5. Factory tunes them rich for safety. 13.1 much too lean so something is amiss if it is showing that.
     
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  5. GrndFnk

    GrndFnk VIP Hellcat Member

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    Does the Shelby WB's toggle around stoich or 14.7, 14.8 to 1 at idle and cruise ? My '09 does but my Cat WB reads out steady in the high 13's at idle when hot and I thought that was odd.
     
  6. GrndFnk

    GrndFnk VIP Hellcat Member

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    These cars still use narrow band 02 sensors for typical closed loop control for driveability, yes ? Or am living in the past .... ?
     
  7. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    the hellcat uses wide band O2 sensor upstream of the catalysts and narrow band O2 sensors downstream of the catalysts.
     
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  8. GrndFnk

    GrndFnk VIP Hellcat Member

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    I would think the narrow band used for closed loop control would be located on the engine side before the cats....or upstream. Huh.
     
  9. usmc341

    usmc341 Gold Member

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    Yes GT500 14.7 at idle and cruise, in the 10's at WOT. I haven't checked my HC. Will do so today
     
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  10. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    Wide band sensors used for closed loop feedback.
     
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  11. GrndFnk

    GrndFnk VIP Hellcat Member

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    Thanks man for the heads up......it is interesting because i have not seen it done this way before.
    That explains why I don't see the FA toggling at idle.
    So I am wondering about the rear narrow band sensors....they basically just tell the PCM if the cats are alive or not and can be turned off ?
     
    Last edited: Feb 8, 2016
  12. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    They also help set the upstream goal voltage but that doesn't seem to prevent people from turning them off.
     
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  13. Snappycat

    Snappycat SRT Hellcat Moderator Staff Member

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    I don't know what the heck you guys are talking about....but it sounds impressive...LOL:p
     
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  14. FarAwayFromHere

    FarAwayFromHere Gold Member

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    These are newfangled speak...
    In laymans old school it's
    umm almost kinda jetting a carb:rolleyes:
    Haha
    Somehow I don't want to have to wrap my skull in this grey matter?:confused:
    Let's get into it shall we....
     
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  15. GrndFnk

    GrndFnk VIP Hellcat Member

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    I will attempt to give a basic explanation and Fnkychkn is welcome to step in anytime and correct me. He be da man.
    USMC your input is noteworthy as well. Thanks for that. And thanks to the rest of you folks for chiming in, I will do what I can here to shed some light.
    Appears the company switched over to using a more precision oxygen sensor to do the work in the trenches for the fuel control .
    The screen up front has a fuel-air ratio readout and that number starts out its life under the car at the wide band oxygen sensors.
    That is a critical sensor and the aftermarket has had them available for years. It is used by tuners everywhere to setup fuel curves
    because the tuner can read the actual fuel air ratio averaged out per bank, make adjustments and go from there hence before this era people were flying blind, reading spark plugs, reading piston domes, etc, and some folks still use some of these techniques with great success.
    In the modern era for the majority, the wide band was the best thing to happen since sliced bread.
    On our cars this sensor most likely does some WOT (wide open throttle) correction as well, similar to the capabilities of the aftermarket computers, or PCMs like FAST, Big Stuff 3 , etc typically used in hot rods and race cars.
    Therefore, we must take care of this little guy under the car because if it OD's, bad things could happen. Gasoline additives like MMT boosters (The stuff that turns the spark plugs orange or red) are NOT advisable or any additive for that matter and it says so right in the owners manual. They can, and do coat the sensors, as well as leaded gas but I have gone an entire summer
    using a wide band with C-16 leaded racing fuel in another vehicle and the sensor continued to function. But lead isn't good for it plus it will kill a catalytic converter in no time.

    Now back to my original question. If you folks get a chance to look up the fuel air ratio on the screen I am curious as to what you are getting at various times when the car is warmed up.
    Thanks.
     
    Last edited: Feb 9, 2016

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