| Author | Message | ||
     Bueller83 |
What is it i had someone tell me it may be my problem but i can not find it in my manual | ||
| Gemini |
wwww.ecmspy.com | ||
| Swordsman |
Adaptive Fuel Value. It's a variable used by your ECM to keep the air/fuel ratio correct despite temperature and altitude changes. It's constantly fluctuating, but it's sometimes slow to compensate for atmospheric changes, and can temporarily make your bike run a little rough (until it has time to "learn" the new conditions). Usually it's the TPS that causes the minor problems, which is the Throttle Position Sensor. On pre-2008 models, it has a tendency to get out of sync with everything else, and needs to be zeroed out. When this happens, it sends incorrect data to the ECM about how open your throttle is, which throws a monkey wrench in the fuel injection calculations and causes poor running. Instructions on fixing this can be found at the link posted by Gemini above. I'm sure someone will point out the forum's Search feature, but given the amount of ECMSpy info flooding this forum and the unpredictability of the local search engine, I know it can be hard to track down some of these simpler questions.  ~SM (Message edited by Swordsman on October 23, 2008) | ||
| Js_buell |
They adjusted it on my bike this week it was at 85% when it should have been at 100% the tech told me and I guess that is in line with my temp sensor being completely out of wack too. | ||
| Jos51700 |
That tech is a moron. Get a new one. Seriously. | ||
| Iamarchangel |
A new tech or a new sensor, or both? | ||
| Jos51700 |
New tech, that actually has a clue. | ||
| Typeone |
to be fair, if one of the sensors was shot or 'out of wack', it could most certainly throw AFV off leading to poor running. if the tech just reset it for the hell of it 'cause it wasnt at 100% and explained he just majikally fixed your bike, yeah, then i agree... get a new tech. | ||
| Js_buell |
Guys, relax here they also replaced the engine temp senor. I just meant that the bad temp sensor might have thrown off my AFV | ||
| Typeone |
 | ||
| Jos51700 |
It's nothing to do with the ET sensor throwing off AFV. It's "They adjusted it on my bike this week it was at 85% when it should have been at 100% the tech told me". Anytime anyone tells you the AFV "should be" a specific #, they are about as far from understanding DDFI as they can get. | ||
| Id073897 |
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| Punkid8888 |
But..... If the engine temp sensor were bad, lets say it reads real low, now the ECM is compensating its fuel tables for the given temperature, colder = more fuel. but since the bike is constantly monitoring combustion through the O2 sensor it will then have to correct the fuel maps with the AFV to get the desired O2 reading. So I think a bad ET sensor will throw off your AFV. It might even be able to compensate enough that it still runs good but that does not mean its correct. an AFV of 85 is board line of normal and abnormal. Putting the AFV back to 100 is a good starting point when ever diagnosing. you always want to see if the problem can duplicate its self. | ||
| Jos51700 |
That's my point. The tech wasn't diagnosing. He thought it was supposed to be 100. It's not. There is no normal/abnormal with AFV by itself. Never has been, never will be. There is only normal/abnormal for a given bike/rider/locale. | ||
| Sharkytattoo |
Optimum AFV is at 100%. Allowable variations are +/- 10%. Meaning nothing above 110 or below 90. If your AFV is at 85%, that indicates a problem. O2 sensor, TPS, intake leak, exhaust leak, dirty air cleaner, could all cause issues with AFV. If your tech just reset it to 100%, it'll go back to 85% as soon as it goes into closed loop. He fixed the symptom, not the problem. | ||
| Jos51700 |
Sigh. THERE IS NO OPTIMUM AFV. If it's s'posed to be 100, how come it doesn't stay there? | ||
| Js_buell |
If your tech just reset it to 100%, it'll go back to 85% as soon as it goes into closed loop. He fixed the symptom, not the problem. If you read all the thread you will see that I said he replaced my engine temp sensor and then reset the AFV to 100, maybe he put it there just for a ball park setting not meaning it has to be 100 | ||
| Turk |
maybe he put it there just for a ball park setting not meaning it has to be 100 It's standard procedure. If you're at a higher altitude or if your bike is just one that runs at something a little different it will learn back to that. | ||
| Bombardier |
It does not stay there because we all operate our bikes in places different from where the original altitude, temp etc was taken into account for the original programming. With ecmspy giving you the ability to adjust for the least amount of variation by customising the fuel map to begin with for the area you ride. The et sensor controls/adjusts both the fuel and spark depending on the temperature sent to the ecm. If this has shifted or the cable is damaged then the afv will be of as the ecm will only read what info it is given and will not know if its right or wrong. It will just apply the corrections as it is supposed to. The ddfi system allows for the variations in temp altitude etc by adjusting the fuel value to compensate with the information supplied to the ecm by the tps,iat, O2 and et sensor. If this was not so we could only ride our bikes at the optimum where they were originally programmed. That is why it does not just stay there. | ||
| Jos51700 |
There is no fixed value for the AFV, because it is "Adaptive" [Fuel Value] It is supposed to change, based on conditions. Since it is supposed to change, there is NO "Ideal" value. When I asked why it doesn't stay there, I was trying to make my point: THE AFV IS SUPPOSED TO CHANGE. Therefore there is NO "ideal" value. Saying it "Should be XX#" is like saying that every person on the planet should be XX# of inches tall. The original programming covers all the bases. The ECM is not optimized for where it's originally programmed, and then the ECM "compensates" for other conditions. The ECM is programmed for the internal combustion engine's ideal fuel and spark requirements, and then it uses inputs to determine an AFV, and then bases it's fuel and spark timing outputs on that AFV. (Buell's in East Troy don't have AFV's of 100, either) An AFV of 85 is pretty low, but there are parts of the country where it's "Normal", and every EFI Buell you run there is going to have a similar AFV. An AFV of 150 is pretty high (maxed, actually), and for my area, that indicates a problem, BUT an AFV of 150 is not "wrong". It's simply the bike setting itself for where it needs to run. I know some Buell's in sea-level/below sea-level regions routinely post AFV's in the mid 120's. Nothing is wrong, it's simply what the air density and humidity of the region require. | ||
| Turk |
From Jos51700's profile - I am an egotistical prick. OK, but at least what you said is right...  | ||
| Jos51700 |
I'm a prick, but an honest and knowledgable prick  | ||
| Gemini |
i would imagine that when the bike was designed, they intended for 100% to be at what ever they design the "ideal" enviorment to be. temp at x. baro pressure at y and humidity at z. this by no way means that the bike should run at 100 or be fixed at 100. like everybody has said so far, it takes alot of factors that will change it. | ||
| Aptbldr |
My goal is to achieve 100% as an average value: sometimes more, sometimes less; but, varying both sides of 100%. Michael Cobb provided custom fuel maps for my XB12R that significantly changed its engine performance character. 1st trial today: woo-hoo! | ||
| Gemini |
mike does have some nice tricks to make the bike feel real good. agreed, to try and achieve a closed loop tuning that keeps the afv closer to 100 is a nice goal. i personaly am very happy if i keep it in the 95-105 range. to moniter that goal, i just do a data log. this way i can my variations of afv and they are under the same weather conditions | ||
| Bombardier |
My goal is to achieve 100% as an average value: sometimes more, sometimes less; but, varying both sides of 100%. +1 Aptbldr I agree with you Jos51700 in that it should change. Ideally it should hover around the 100 which is where ecmspy comes in. It gives us the ability to change the mapping to suit our usual riding conditions with the AFV adapting if we go outside them. An afv of 85 tells me that either it is running way rich or that there is a sensor that has shifted(et sensor) or is fouled(O2 sensor). | ||
| Id073897 |
My goal is to achieve 100% as an average value Why 100%, taking into account what has been (fully correctly) said about the meaning and use of AFV? Why not 98.3 or 104.9? Why is it better to have AFV set to some number instead of using the AFV to adjust mixture as required? Please explain. Regards, Gunter | ||
| Gemini |
it's not better to have the bike at a fixed value. i think it is better to have the closed loop area tuned it a way that it stays close to 100 by itself. if i go on a ride and it stays at 95 the whole ride, then i am happy. if the bike is going from 85 up 115 in one ride during the same conditions, the bike is going to feel different in the open loop areas. it will feel inconsistant | ||
| Aptbldr |
My goal is to achieve 100% as an average value <snip> Gunter asked, "Why not 98.3 or 104.9? <snip> Please explain." Seeking an average around 100%; I would be satisfied within 98.3 to 104.9 range of values described by Gunter. jsj | ||
| Gemini |
agreed. in fact i am happy with a 10 point range myself | ||
| Jos51700 |
"An afv of 85 tells me that either it is running way rich or that there is a sensor that has shifted(et sensor) or is fouled(O2 sensor)" Don't ride it up Pike's Peak, then.....  |
