| Author | Message | ||
     Madsx |
Explanations, Definitions or whatever ya got. I'm not picky Fun Times  | ||
| Buelldyno_guy |
Check the following thread "S3 Power Commander maps for XB" there has been an on going discussion on Buell fuel injection. The "Closed Loop" area in the ECM is where the 02 sensor helps control the Air/Fuell ratio. The "Open Loop" section is where the value is not being controlled or modified by 02 sensor input. | ||
| Fullpower |
look here for some illumination http://cds.h-dnet.com/docent/cds/BUELL700/ref_content.htm | ||
| M1combat |
Do a search on the site for "AFV"... That should bring up LOTS of information. We've discussed it many times  . To add to Bdg's statement... The AFV (adaptive fuel value) gets adjusted to a certain number (between 85 and 115 I think) based on what A/F ratio the O2 sensor is seeing. It tunes for a less than optimal (for power anyway) A/F ratio. This tuning only happens in closed loop mode. The ECM then uses the AFV to adjust the level of the fuel curve (but NOT the shape) in the open loop mode. This works exceedingly excellent as long as you don't make any major mods to the intake/cams/heads/valves/exhaust etc. Once you change the VE (Volumetric Efficiency) curve then the AFV's modification to the open loop portion of the fuel system becomes somewhat problematic. It insists that your VE curves are the same (because that's what it's programmed for) and really throws off the fuel mixture both above and below the RPM where you "settle" the AFV. The PCIII will fix this. There is also a tool being developed to allow re-mapping of the Buell stock/race ECM's. When this tool is done (I hear it's VERY close  ) it will be a glorious day indeed . From what I hear though, it will only be sold to HD dealers, so for the most part we'll still need to bend over for dyno time to get our bikes tuned... On second thought, maybe not so glorious... | ||
| Buellj79 |
Don: glory has a price.  J | ||
| Opto |
Don, they've always had this tool. If I'm wrong then I'll have to bend over...:0 no way. I couldn't wait and don't want to pay, therefore went my own way. BTW the stock XB12 ecm is really quite a good forgiving unit. It'll handle a K&N and a standard Drummer no worries at all. And the less advanced ignition timing means you can run less than optimum fuel. Maybe not the king of all mods/big HP but not to be underestimated. Madsx the search function is down, otherwise I'd link you to a post I did about a year ago. The link posted above is pretty good. | ||
| Rageonthedl |
The first type of EFI system operates as an OPEN LOOP system. The ECM calculates and delivers spark and fuel based on a set of predetermined spark and fuel "maps." These "maps" provide the base information necessary to run the engine with only minor adjustments for external/internal environmental conditions. This method is accurate to the degree that the "maps" are accurate. The Harley-Davidson systems are open loop. The second type of EFI system operates as a CLOSED LOOP system. This system not only uses spark and fuel "maps" but also feedback from an exhaust gas oxygen (O2) sensor to continually adjust the amount of fuel delivered. This offers the advantage of "learning" the behavior of the engine over time as well as responding to a wider variety of conditions encountered while riding than that of an OPEN LOOP system. The Buell DDFI operates both as an OPEN and CLOSED LOOP system. This is necessary to adjust for all possible operating conditions. Buell's selection of high lift cams (which enhance engine performance) make it necessary for an open loop system at idle and wide-open throttle. Furthermore, when operating in open loop during cold start and idle, the system will utilize programmed fuel and spark maps in the ECM for ease of cold starting and to provide a stable idle. When the bike is at a steady cruising speed and operated under a light load, the DDFI system switches to closed loop operation. The system then continuously "tunes" the performance of the engine to compensate for changing conditions and provide maximum performance by using the O2 sensors input. OPEN LOOP Idle and starting slow speeds under 20mph (1500 rpm) High speeds above 60mph (4,000 rpm) accelerating from low speed accelerating from high speed decelerating CLOSED LOOP Cruising between 40 - 60 mph at operating temp. (1500 to 3500 rpm) | ||
| Fullpower |
"bend over for dyno time" Do I need an appointment, or is it "first come first serviced?" | ||
| Jlnance |
The terms open loop and closed loop come from control theory (the engineering kind, not the psychological kind). The idea is that you have a system with certain inputs you can adjust, and with an output you desire. The term open loop means that you adjust the inputs with out looking at the output, while closed loop means you do look at the output when adjusting the input. These terms are used because if you draw a picture of what is happening, the closed loop system will have information flowing in a circle. An open loop system will have a segment of the circle missing. Generally, closed loop systems work better. However they are slower than open loop systems, and are also less stable, so there are times when open loop is better. | ||
| Blake |
All the bast humans I have encountered run primarily in closed loop mode. |
