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  #1  
Old 07-12-2010, 03:10 PM
Comingapart Comingapart is offline
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Default Oxygen sensor output

Just me thinking here, if the only A/F measurement these bikes are using is oxy sensors, can't the fuel mixture be adjusted by simply altering the oxy. sensor signal?

Something as simple as unplugging the o2 sensors and replace them with a resistor? Or a simple circuit with a pot to have an adjustable range?

Or, the ideal situation may be to place a resistor inline with the o2 sensor to simply reduce the output by a small margin, that way there would still be some tuning changes to account for temperature.

Provided this would work, any idea how I could figure out what resistor values to use, without having access to any way to measure A/F Ratio?
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Old 07-13-2010, 08:59 AM
lonestar17 lonestar17 is offline
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it has been done in denmark and sweeden ....but why would you want to mess about with millivolt resistors 1 when you could jus go and buy screaming eagle supertuner and 2 when the o2 sensors are by far not the only sensors that are used to asess fueling there are others that are not disclosed.
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Old 07-13-2010, 02:59 PM
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07RoadHawg 07RoadHawg is offline
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To answer your question... Yes, you can control the fuel delivery by changing the O2 volts the ecm sees and making it thing the engine is running leaner than it is. Nightrider has IED (inline enrichment device) that plugs in between the O2 sensor and ECM and will add fuel. Keep in mind this adds fuel across the board and will work for simple mods like an air cleaner and exhaust swap. Past that, you will need to get a tuner of some sort.

No "double top secret" sensors on the bike to control fuel. Newer models use MAP and others use TPS. They all use engine temp, and the '07-up use O2 to run in closed loop mode, and they use some sort of a VE table to tell the ecm about the air flow in the engine at a given RPM/TPS.
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Old 07-13-2010, 03:22 PM
Old Gunny Old Gunny is offline
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The VE table (Volumetric Efficiency) are one of the tables the ECM uses to put in the fuel the engine wants.
The way these later tuners, TTS or SEST, use this to help get the correct tables (TTS with "V-Tune" for sure) is to go all Closed Loop on the AFR table. Puts the whole thing in Closed Loop.
Since the ECM will now adjust itself to get the correct O2 it wants to see, the place it changes things is the VE tables. This can be saved with the V-Tune program. This info can be put back into the ECM.
Do this a couple 3 times and you have a pretty good idea what the whole engine wants.
Then only run Closed Loop in crusing areas. Outside that though the VE tables are pretty much correct. Thats the double secret.

Last edited by Old Gunny; 07-13-2010 at 03:24 PM..
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Old 07-13-2010, 03:59 PM
lonestar17 lonestar17 is offline
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I agree with what everyone is sayin (although all a little vague on details) yes the tuner programs can adjust the fueling on the bike automatically its a function on sest call "smart tune" we lie to the ecm even with this program though and say its volumetric efficiency expressed as a percentage is either better or worse than it genuinely is. as to the "double top secret sensing" ask your dealers about ION sensing then comeback and tell me that doesnt have any effect what so ever on fueling of the bike. if you are going to fit only a air cleaner and exhaust system i sugest (unless your valentino rossi riding a harley at laguna seca and lets not forget thease are harleys at the end of the day) the bike will compensate for this as they have a 10% learning capacity. wich i think was breifly mentioned in a different post. All in all you can be bill gates on a computer but if you cant build and engine choose the correct parts and undestand the effect of fitting each parts on the engine and the efect of the button your going to press then its not worth the rather large bill that you will acumulate through trial and error. :icon_cra ckup:
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Old 07-13-2010, 04:36 PM
Old Gunny Old Gunny is offline
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The thing we are all talking about is the same thing.


One thing --The TTS and SEST and maybe some others, when you use them you are not lying to the ECM.
You put in the Actual Program the ECM uses to run the engine. It is the real thing.

The physical engine is the same my GrandDaddy worked on in 1920, my Daddy in the 30's.

The thing that has chaged is the way the engine is supplied fuel how the ignition system works, though the latter is almost the same except for the computer controles. And Ion sensing

Something everyone has to think about is this is the way things are now. My GrandDaddy and Daddy had just as much new stuff coming along in 1930 say as we have in 2010. And a lot less resources. They can do it ,I can.

And I am 72 years old. Damn near seen it all. I have seen pigs fly.

What you are vague on, study up. Easy to do now-a-days. Plenty of folks to help.

Point is, it is easier to go with this flo, than worry yourself about it.

Put I don't think I will ever learn what Blu-tooth or Gen3,4 I-Phone is all about. Rather ride that learn that.

Last edited by Old Gunny; 07-13-2010 at 04:41 PM..
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Old 07-13-2010, 07:36 PM
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07RoadHawg 07RoadHawg is offline
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Gunny has it right yet again ls..... Pull your head out of the sand, keep reading, and you might learn something just like the rest of us have.

As for the icon you keep using, that is typically used when you are quoting a previous post and agreeing with what somebody said, not for calling them stupid. If you want to call someone stupid, learn up a bit and then just come out and say it.
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Old 07-14-2010, 07:25 AM
lonestar17 lonestar17 is offline
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haha maybe its just my english way of saying things but it seams some of you are insulted.... my apologies. as to the pull my head out of the sand and learning things...if you would all jus take a step back and try to see it as not insulting you but trying to help you then you may get an incling as to what and whom i am working for and i have also see pigs fly a bit of a sight if im honest ....
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Old 07-14-2010, 10:16 AM
Old Gunny Old Gunny is offline
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Sorry bub, I though you were working for yourself and your bike and the enjoyment of being self reliant and taking care of yourownself.
I didn't know.
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  #10  
Old 07-14-2010, 10:50 AM
lonestar17 lonestar17 is offline
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No Bub i dont ....
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Old 07-14-2010, 10:50 AM
 
 
 
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02, air, davidson, harley, intake, o2, output, oxygen, part, problems, replace, resistor, sensor, sensors, voltage


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