adaptive fuel value (AFV)
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From: wet coast BC
adaptive fuel value (AFV)
Using SEPST tuner you usually check the reset AFV on a re-flash of the ECM. OK, it resets adjusted fuel to 0?
Why was it not at '0' in the first place?
And why are we not able to see what the AFV is at before resetting it in the ECM?
Anyone figure this one out?
Why was it not at '0' in the first place?
And why are we not able to see what the AFV is at before resetting it in the ECM?
Anyone figure this one out?
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From: wet coast BC
any ideas at all
any thoughts?
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From: Vancouver Island B.C.
The AFV cells store the long-term learned fuel correction (trim) over the closed-loop operating range. When a calibration is flashed into the bike, these cells need to be cleared so they do not influence the calibration. These cells are spread out and there are different amounts depending on tuning devices. Where they are and their values can not be seen. They should be reset when you do something like clean or replace your air cleaner. They can also pull a tune out if the o2 sensors are not installed properly in an aftermarket exhaust. The TTS automatically resets them when you flash a map. It will also allow you to reset them from the datamaster part of the program which means you can reset them on anyones bike.
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From: Ashland Ohio
AFVs are longish term adjustments to the 'map' installed in the bike. They change around based upon gasoline used, etc.(hence the name 'adaptive') AFVs WILL be in play unless one uses the exact same gas all the time. They will NOT be zero. But the closer to zero they can be made the better. To expand on something Russel said... if one installs aftermarket pipes on a bike... if the O2s are not positioned correctly, the O2s will send bad data to the bike, which in turn the bike will use the AFVS to adjust to the bad data, and the bike will end up running like crap.
AFVs are NOT a big issue if everything is normal, but will kill you if the bike is receiving bad data.
AFVs are NOT a big issue if everything is normal, but will kill you if the bike is receiving bad data.
Last edited by wurk_truk; Aug 18, 2011 at 01:05 PM.
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From: wet coast BC
Lonewolf
"trim" sounds right & in closed loop between cells. resetting on a new flash also makes sense. The hidden factor of AFV still has me wondering. If a tuner "ie you" sets up a bike and it runs great out the door, then why would a hidden trim need to make adjustments and not let you see 'what' so you can incorporate that into your tuning. I have read many posters say their bike ran great and then it starts to run like crap, bad tuner. but could it be this AFV trying to adjust towards 14.6 making it leaner? Then when you flash again and reset it runs great again. just saying since I am not sure.
wurk truk
with built in features of the ECM it does adapt to different fuel, altitude and temperature etc. and I agree it adapts or tries to for leaks and bad data and an exhaust change. so when repaired resetting makes sense to save it the time to self adapt. I use 'zero' as a reference to the base, a start point, normal place before adapting starts.
_____
I guess without seeing what it does only leaves to speculation. I read on another forum where someone who tunes on a dyno was puzzled why the tailpipe reading was different than the flashed AFR, it was leaner.
"trim" sounds right & in closed loop between cells. resetting on a new flash also makes sense. The hidden factor of AFV still has me wondering. If a tuner "ie you" sets up a bike and it runs great out the door, then why would a hidden trim need to make adjustments and not let you see 'what' so you can incorporate that into your tuning. I have read many posters say their bike ran great and then it starts to run like crap, bad tuner. but could it be this AFV trying to adjust towards 14.6 making it leaner? Then when you flash again and reset it runs great again. just saying since I am not sure.
wurk truk
with built in features of the ECM it does adapt to different fuel, altitude and temperature etc. and I agree it adapts or tries to for leaks and bad data and an exhaust change. so when repaired resetting makes sense to save it the time to self adapt. I use 'zero' as a reference to the base, a start point, normal place before adapting starts.
_____
I guess without seeing what it does only leaves to speculation. I read on another forum where someone who tunes on a dyno was puzzled why the tailpipe reading was different than the flashed AFR, it was leaner.
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From: Vancouver Island B.C.
Lonewolf
"trim" sounds right & in closed loop between cells. resetting on a new flash also makes sense. The hidden factor of AFV still has me wondering. If a tuner "ie you" sets up a bike and it runs great out the door, then why would a hidden trim need to make adjustments and not let you see 'what' so you can incorporate that into your tuning. I have read many posters say their bike ran great and then it starts to run like crap, bad tuner. but could it be this AFV trying to adjust towards 14.6 making it leaner? Then when you flash again and reset it runs great again. just saying since I am not sure.
"trim" sounds right & in closed loop between cells. resetting on a new flash also makes sense. The hidden factor of AFV still has me wondering. If a tuner "ie you" sets up a bike and it runs great out the door, then why would a hidden trim need to make adjustments and not let you see 'what' so you can incorporate that into your tuning. I have read many posters say their bike ran great and then it starts to run like crap, bad tuner. but could it be this AFV trying to adjust towards 14.6 making it leaner? Then when you flash again and reset it runs great again. just saying since I am not sure.
I would suspect that the ve tables were not calibrated properly. The first thing in tuning is calibrating the ve's so the tailpipe reading matches the desired afr.
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From: Ashland Ohio
1Canuck, you missed the point. Its not adapting to having bad data, it is adapting because it is USING bad data. The ECM doesn't know it's 'bad'. So if a tune degrades over time and runs like crap a month after a tune... it is the AFVs adjusting the tune in a direction it should NOT be going because the data it is receiving is crap. Garbage in/ garbage out.
It is ALL about the O2 sensors. Nobody here seems to check them much and trusts manufacturers. ONLY manufacturer I would trust is Fuelmotos 2-1-2 pipe. Not naming names, but some pipes have: O2 at wrong angles (see above); some use a punch for the O2 hole before welding the bung and that leaves a tulip of metal surrounding the sensor in the pipe; some are not deep enough to work; some have a way smaller hole in the pipe than the O2 bung, etc. The FIRST thing a pro tuner OR a DIYer needs to do is check the O2 protrusion on EVERY pipe installed.... unless it's an open loop tune using a sniffer. I believe that even an open loop tune, if using bung holes, the O2 placement needs checked.
I'm not going to get into that dyno tuner, but the closer the bike is dialed in, the better AFVs work... and they ONLY work if there is a section of the tune in closed loop. If the whole tune is open loop, the AFVs are not an issue. Also, remember a couple more things. If a bike does have a section of closed loop, then also the open loop areas of that tune will be effected by the AFVs. ANd further, that open loop section cannot be driven leaner by those AFVs, only richer. Again...it, in the end, is all about the VEs. If the VEs were right, on the suspect bike, then there simply would be NO WAY to see it leaner than set, if one was looking at the open loop section. Closed loop section WILL be driven leaner by AFVs.
Some of us surely WOULD like to look at trims. Be a good indicator of things gone wrong for sure.
Last edited by wurk_truk; Aug 19, 2011 at 03:18 AM.
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From: wet coast BC
Thank you for the input. I should have mentioned my VE & VE new are very close in all areas but not always the same in a particular cell. I do data runs for the heck of it now just to see if there are changes.
we seem to have an agreement that if the VE front and rear are set correctly then AFV does not come into play.
Therefore as long as my data runs have VE set & VE new in agreement then the AFV does not come into play, unless it smooths out between adjoining cells. otherwise an adjustment is made but not disclosed via the VCI or TTS tuners, or any other device at this time. The only way to check this is to use a sniffer to read the AFR out the exhaust right after a tune and then at some time later to see if ECM made changes behind the scenes.
we seem to have an agreement that if the VE front and rear are set correctly then AFV does not come into play.
Therefore as long as my data runs have VE set & VE new in agreement then the AFV does not come into play, unless it smooths out between adjoining cells. otherwise an adjustment is made but not disclosed via the VCI or TTS tuners, or any other device at this time. The only way to check this is to use a sniffer to read the AFR out the exhaust right after a tune and then at some time later to see if ECM made changes behind the scenes.
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From: Ashland Ohio
I will use a twin scan, because THAT device will tell us what AFR the bike is outputting via the ECM (desired AFR), AND what the bike is REALLY outputting via the O2s.
We all know that if a bike is set up to run even ONE cell in closed loop... the AFVs can and will affect the open loop sections of that tune, too.
The old delphi software dude on HTT, FBRR... told me that if the bike is in closed loop... the open loop sections of a closed loop tune will NOT go leaner, only richer. Which I think is way cool, but want to check this out.
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