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Old 11-17-2012, 11:58 AM   #118
roger 04 rt OP
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Earlier in this thread I presented an incorrect explanation of how the Power Commander III USB with Wideband O2 operated when integrated with the Motronic MA 2.4. The reason for this error was an omission in the Power Commander installation manual for R1150RT. Here is the correct explanation, please refer to the diagrams at the end of the thread.

The Power Commmander III with Wideband O2 for BMW R1150 and R1100 is actually two different functions in one package. One function is that of the Power Commander III USB an Add-On Fuel matrix of values according to RPM and TPS. The second function is much like that of the Innovate Motorsports LC-1. Rather than recapitulate the Add-On Fuel function you can read about it here: Power Commander III USB.

The second function, Wideband O2, functions just the same as an LC-1 Wideband O2 controller. You can read about that in detail earlier in the thread. In short, you replace the stock Narrowband O2 sensor that has a fixed transition point at 14.7:1 AFR (actually Lambda = 1, meaning that theoretically all the oxygen has been consumed) for a Bosch LSU 4.2 Wideband O2 sensor which has a programmable transition point. By selecting a Lambda value less than 1, the Motronic will automatically richen the mixture in the Closed and in the Open loop fueling calculation. I'll rephrase that: if you drop Lambda to 0.94 the Motronic will run Closed Loop at 13.8:1 which is 6% richer than stock 14.7:1. Then through the magic of the Motronic's Adaptation Values capability it will also add fuel to all Open Loop fueling calculations after a "learning" period.

The "learning" period takes some time and is not quite perfect because you have to drive your motorcycle at steady throttle for enough time in Closed Loop at a range of throttle openings and RPMs for the Motronic to "learn" the full adaptation map. It is likely that there are fewer Adaptation Values than cells in the Base Fueling Table of the Motronic, which means that there is likely a coarser correction. But I've measured it, and Adaptation works effectively, it just takes a while. The bigger the shift in Lambda that you're making, the longer it seems to take to "Adapt".

There is a way around the "learning" time. In short, find a way to either a) add a percentage of time to the pulse coming from the Motronic; or b) increase the fuel pressure so that the pulses coming from the Motronic deliver a percentage more fuel than stock. Since the Innovate Motorsports does not have an Add-On Fuel map I added a Fuel Pressure regulator and boosted the fuel pressure. However, if you use a PC III USB, you can add the fuel through the fuel table function.

Looking at the sample Add-On fuel tables below, if you fill in the fuel matrix with a 6% addition in every cell at 60% throttle and below, and then reduce to 4% more fuel at 80% throttle and 2% fuel at 100% throttle you will have a sound starting point. Note that this approach acknowledges the great work that BMW has done in their design of the Base Fuel Map in the Motronic; it just adds a proportional percentage to account for the amount of richness you want to add. I'm sure this seems like a simplistic use of the Add-On Fuel function of the PC III but it will work and you won't need to add a BoosterPlug or Fuel Pressure regulator.

I'll end with a short comparison of LC-1 and PC III. Both are technically sound methods for controlled richening of the Oilhead's mixture, leading to much better driveability and a bit more power in the mid-band (2000-5000 RPM) which it achieves by moving up the AFR vs Power Curve earlier in the thread. (There will not be an increase in WOT horsepower because the BMW fuel tables are already near Best Power Mixture there.)

Advantages LC-1:
--Lower cost: $170 for the LC-1, $395 for PC III (although I've seen PC III for $285)
--Calibration function for the Wideband O2 sensor
--Datalogging of the realtime stream of O2 readings
--AFR gauge included in purchase price. It is an add-on for the PC III.

Advantages PC III:
--Plug & Play: The PC III has all the connectors you need to plug it in out of the box. For the LC-1 you need to wire your stock O2 sensor connector and also power leads to its cable.
--Built in Add-On fuel capability. If you use the LC-1, you either wait for Adaptation, add a BoosterPlug which shifts fueling a fixed 6% or, as I did, increase the fuel pressure. A good fuel pressure regulator costs around $100.

RB

I've been doing some more research on the Power Commander so I'd like to update the Notes section but can't go back to edit it. Here are the notes with updates, 5) and 6):

Notes
1) I am trying to get a PC III w/Wideband but have not run one yet.
2) The fuel table on the PC III allows you to enter percent increase/decrease. Typical injectors have a 1 mS dead (on/off time), I don't know if the dead time is taken into account by the PC III.
3) At 7250 RPM the injectors fire every 8.3 mS. The longest injection pulse that I've seen is 8.2 mS. This points out that you can't add 5% to the longest pulses with making them longer than the frequency of rotation in some cases. (However, the vast majority of the time injection pulses are less than 4 mS.)
4) I don't think there's a problem but I can't tell how the PC III responds to Overrun Fuel Cutoff when no pulses occur (i.e. the PC III isn't getting any engine speed info during that time.)
5) Because the Powercommander gets its +12V from the injectors/fuel pump and since the fuel pump goes off after a couple seconds, Dynojet recommends hitting the starter button before the fuel pump cycles off.
6) The Powercommander DOES take injector dead-time into account when adding/subtracting fuel.






roger 04 rt screwed with this post 11-19-2012 at 11:36 AM
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