| Author | Message | ||
     Saltypistachio |
I was curious how/if one could tune for boost with direct link... I know this Buell EFI does not reference a map sensor which would read the positive pressure, like many of the cars I have had the privilege to play with. Would I just have to just enrich the higher rpm/tps data expecting them to be used during boost, and risk running rich while in vac? I know at high throttle angles, regardless of enigne speed, it will be inevitable that I will force boost, but its the in-between I’m worried about (high rpm, low throttle angle). Any and all info would be greatly appreciated! dan (Message edited by saltypistachio on August 05, 2006) (Message edited by saltypistachio on August 05, 2006) | ||
| Odinbueller |
Well, I admittedly have no experience with Direct Link or turbo boost parameters, however, the Buell DDFI II system is an AlphaN system, which uses the TPS, narrow band O2 sensor, and the Adaptive Fuel Value (AFV) to monitor and adjust combustion. In regard to the turbo, the AFV will be the big hurdle I think, and Dynojet spent thousands upon thousands of man hours in support for the Power Commander because of it. Here's why: All Buell DDFI motorcycles shipped from East Troy are sent with an AFV of 100%. The AFV monitors combustion through the narrow band O2 sensor to see if it is running too lean or rich. Once the motorcycle is run closer to sea level in closed loop mode, the ECM sees that the O2 sensor is sending more lean results as opposed to rich, and automatically adjusts the fuel pulse width to correct it, which results in a lower AFV value. I think I remembered that right from school  Conversely, and everyone with a DDFI Buell should know this little tidbit, if you start to run out of gas, the ECM has no idea that the fuel tank (or frame) is low on fuel. The little "Feed Me" light is an independent circuit from the ECM, and it controlled by a thermistor that heats up once the fuel level drops below it. The thermistor lights up the "Feed Me" light to let you know to gas up. That's why sometimes it takes a while for your "Feed Me" light to go out after a refueling. Anyway, the ECM sees that you are starting to run lean due to lack of gas to squirt through the injectors, so it richens the mixture, in effect lowering your AFV. Many people have run out of gas on a DDFI Buell and were surprised that they were unable to restart their bike after filling up because the mixture was so rich, it gas fouled the plugs. So, any time you run out of gas, you will need to reset you AFV back to 100%, and go for a ride to have the ECM re-learn your particular AFV climate & pressure. It is this fluctuating map in closed loop operation that makes it extremely hard to tune things like this. However, the Direct Link may be different, I don't know. But Dynojet dropped their support of Buell Motorcycles because of the AFV. Hope this helps. Chris | ||
| Teeps |
Odinbueller Posted on Saturday, August 05, 2006 <massive-snip> Anyway, the ECM sees that you are starting to run lean due to lack of gas to squirt through the injectors, so it richens the mixture, in effect lowering your AFV. Many people have run out of gas on a DDFI Buell and were surprised that they were unable to restart their bike after filling up because the mixture was so rich, it gas fouled the plugs. So, any time you run out of gas, you will need to reset you AFV back to 100%, and go for a ride to have the ECM re-learn your particular AFV climate & pressure.} All I can say is; What!!!? I know enough about F.I. (to be a danger) but I've never heard of such a thing... However, if it is true (and I'm dubious that it is), that is a serious design defect. And at the VERY least should be documented in the owner's manual.} | ||
| Odinbueller |
Well, I know that it sounds strange, but this was conveyed to me by Gary Valine, the guy who helped design the DDFI system. Actually, as long as your feed me light works, you should have no problem. It's just the way the DDFI system works. If you see the AFV map curve, it kinda clarifies this. Also, if you do get the bike started after refueling, and you can get it back to closed loop mode, you could burn off the excess gas and clear off the plugs with a good dose of WOT. (Message edited by odinbueller on August 07, 2006) | ||
| Al_lighton |
DDFI corrects for conditions that are making the bike run leaner by raising the AFV, not lowering it. The AFV is one of the scaling mechanisms adjusting the injector duration calculated from the map seed values. Higher AFV's lengthen injector duration, lower AFV's shorten it. It is true that when the bike starts to run out of fuel, the bike starts to get leaner, and if it is running in closed loop learn mode, the AFV calculations will result in the AFV climbing higher. However, Buell has improved the running out of gas algorithms, and only the very early DDFI bikes had "runaway" AFV problems when running out of gas. It does go up, however, and the combination of the cold startup enrichening and the raised AFV can in some cases foul a plug. It isn't a usual thing, but I would take the bike into closed loop asap after running out of gas to get the AFV back to where it needs to be. There is a natural tendency to jack the throttle off and on on a bike that is sputtering when it is running out of gas. This will prevent the ECM from entering AFV learn mode anyway, so the AFV isn't as likely to slew rapidly. I've run my 99 S3 out of gas a couple times, never had a problem with it running right after I put gas back in it. But I have heard of folks having problems with their bike running like crap after running out of gas. | ||
| Odinbueller |
I was afraid I got it backwards. Thanks Al. I just remember the example given at school and thought it would be relevant here. | ||
| Saltypistachio |
That right i do remember reading something similar at the direct link post. Hmm... so how to overcome that AFV factor? I bet this guy (ERICZ) has some answers... http://www.badweatherbikers.com/buell/messages/3842/204705.html?1154699516 | ||
| Firemanjim |
Salty,might be able to overcome with a boost referenced fuel pressure regulator--you would have to bypass the stock set-up somehow.I know there are piggyback boxes around on some other turbo bikes that use boost reference(Wayne at Tuneboy makes some for Triumph)might also use an injector that flows more in conjunction with the regulator. I will be pursuing this myself for the next gen Bonneville bike as I want to FI the Garrett set-up I will be using. |
