2004 R1150RT Wideband O2 Sensor Project (and AF-XIED for BMW)

Today I had the chance to answer a question that's been on my mind, how would my 04 RT run if I programmed lambda from 0.94 where the Wideband O2 has been (13.8) to a leaner than stock setting of lambda=1.06 (15.6:1)? The answer: Not Terrible.

After programming the LC-1 to the leaner setting, and then resetting the Motronic and removing the BoosterPlug, I ran a 10 mile test loop. At first, during the warm-up phase with enrichment by the Motronic and Open Loop, it seemed fine. But as I passed through 4 bars on the temperature gauge, it was apparent that the motorcycle was noticeably less responsive to the throttle. Then, fully warmed up, I started a climb through the gears, guess what? The motocycle surged around 3000 RPM in second, third and fourth gears--not a pronounced surging, just subtle modulation of the torque and shifting note at the exhaust. I couldn't wait to get back and reset to lambda=0.94.

So what did I learn? There is definitely an AFR component to the Boxer surging phenomenon: 6% leaner than stock is too lean for sure, and I know that 6% richer is great. Where is the spot in between the two ends that is just rich enough? Just a guess, somewhere between 14.0 and 14.4.

The GS-911 time stamps, to the millisecond, all the data it collects. Somewhere along the line it hit me that it could be used as a Inertia Dynomometer since it collects RPM data and the transmission ratios are printed in the R1150 BMW Repair Manual.

I've also been curious about the 1150 Torque at 2000 RPM at a 13.8:1 mixture. The final piece of the puzzle was using some of the HP physics that I boned-up on for the R1150 Gas Mileage thread.

A couple key (rough) numbers:

--8 to 12 ft/sec-squared is a decent rate of acceleration for town and highway driving.

--R1150RT and rider (in my case) weigh about 800 lbs.

--It takes 25 to 30 horsepower to accelerate bike and rider at 8-12 ft/sec2 plus 2-10 horsepower for aerodynamic drag between 30 and 60 MPH

--25 Horsepower corresponds to 65 ft-lbs of torque required at 2000 RPM. But 40 HP translates to only 52 ft-lbs. at 4000 RPM.

Have a look at the chart and data below which were taken in 4th and 5th gear, starting at 1500 RPM and 2000 RPM respectively and with Wide Open Throttle. It looks like (and felt like) there was just enough torque to meet the HP/Torque/Acceleration targets above at about 2000 RPM in 4th gear and about 2500 RPM in 5th.

There's lots to discover but, for instance, look at the 81 degree TPS angle and the 60-70 ft-lbs of torque. Notice too, the relatively flat rate of acceleration from 2000/2500 to 4000 RPM. It's making more HP as it accelerates but air-related drag is increasing too.

The graphs are choppy because I didn't use a high enough sampling rate and drop off at 4000 RPM or so because that's where I let go of the throttle on the in-town road where I was trying this out.

Now that I have about 2000 miles on my '04 1150RT, wanted to see how things have settled in. It has been a couple of months since I last reset the Motronic and cleared any Adaptation Values that might have been "learned" by the Motronic. So I made a couple checks.

First I measured the warm-up transition from start to running closed loop. As mentioned, I haven't reset my Motronic for over a month and have taken many, varied rides. I wanted to see how things looked and whether there was clearly ADAPTATION going on. The results are that the Motronic has "learned" about the BoosterPlug, E10 fuel I run and Wideband O2 set at 13.8:1.

The result that can be seen from the chart below is that everything has been shifted to the desired afr of 13.8:1, including the cranking and warm up period. Booster, E10 fuel and LC-1 are operating in harmony with each other.

Below is the warm-up from a cold (85F is cold today) to hot (Closed Loop) motor. You can see the cranking and afterstart enrichment on the left at about 12-12.5:1, the initial warmup at 13.1:1 (about 5% below 13.8), final warmup enrichment at 13.3:1 (3%) for a few seconds and then smoothly transitioning into closed loop for the right hand half of the chart. The Closed Loop AFR spread is a mere 2.5% because of the speed of the LC-1. Gas mileage from for the most recent tank of fuel running premium E10 was 44 mpg (235 miles and 5.3 gallons).

The lines on the chart are blue 13.8:1 and red 13.3:1.


Here is an Autolite Plug with 2,000 miles of mostly local driving at 13.8.

Just like to say thanks for this thread. Helps me understand why my bike doesn't behave like my old Bing carb one :)

Thank you for sharing all this great information. I am thinking about setting up a dual channel version of this on my KTM. Your findings confirms a lot of my theories about how the modern FI systems work.
These facts also puts many of accepted conclusion to the test. I have never been a believer in disabling the stock O2 sensors and running PCIII units etc..
My KTM has a Keihin ECU but I am convinced that the same logics of operation applies.

Espeacially nice that you confirmed the adjustments made in closed loop carried over to the open loop operation.

Thanks, appreciated.

Those older carbureted bikes ran richer and better, no two ways about it. But they had a lot of Carbon monoxide and unburned fuel in the exhaust.

Interestingly, on the 1100s shipped to Europe, the FI systems were run open loop, and 6% richer than the US Catalytic converter bikes. These bikes are pretty happy at 13.8:1.

Thanks. It took many test rides to confirm much of what's here. It now seems obvious that an ecu designer would want the benefit of having the ecu learn from closed loop operation. One thing that I have not had the time to figure out is the granularity of these learned adaptations. However, I would assume that even, maybe especially, at WOT a designer would want to correct for fuel quality, fuel pressure and fuel injector tolerance.

Here is some other info: http://www.bmwmoa.org/forum/showthread.php?t=59622

Here is a graph that I plotted a few days ago after fully reseting my Motronic, settting the LC-1 to 13.5. It took several rides at many RPMs, gears and TPS positions to relearn the Adaptation Values. Here's the plot, made after a warm restart, meaning that the bike was at temperature and was back in Closed Loop quickly.



What you can see is that for the first 12 seconds (until the 2:27 mark) the bike is Open Loop. In that period there is the After Start Enrichment and Warm-up Enrichment--the up-slope that levels at 13.2. Then at 2:27 it snaps into Closed Loop at 13.5.

What is noteworthy about this plot is that the entire curve has been shifted down by 12% or said another way, the Motronic has added 12% more fuel to both Open Loop and Closed Loop--4% more fuel because I run E10 and 8% more because the LC-1 is programmed to 13.5:1.

If the Closed Loop learning had not been applied to Open Loop (and you can see where Open Loop starts after a Motronic reset in plots from earlier in this long thread, here), The Open Loop phase would have started about 8% higher at 13:1 and the pre-closed-loop plateau would be at about 14.3:1, then it would have snapped down to 13.5 for the Closed Loop phase.

For me, this pretty fully settles the question of Adaptation and whether the Motronic MA 2.4 has that ability or not. Sometime when I get a chance I'll also measure the WOT AFR to confirm Adaptation there as well, but as an Anti-Knock measure, it's just as important to have Adapted there so I don't expect any surprises.

RB

PS: An IIce Air in the 30C position would be a good alternative.

In the prior post I showed that the Motronic had Adapted Open Loop fueling, without a BoosterPlug or any other modifications, to the 13.5:1 AFR that the LC-1 Wideband O2 replacement is set to.

Because the move from 14.7 plus the leanness of E10 requires the Motronic to add 14% to the stock fuel tables to reach 13.5, and because adaptation is deliberately a slow process, it took several rides over several hours for the Motronic to dial itself in.

Next I wanted to see how quickly it would Adapt if I shifted the IAT sensor by 30C, an 11% increase in fueling, such that the Motronic only had to move the last 3% (14% - 11%).

I wired the BoosterPlug (an iice air in the -30C position would have worked nicely but the bp was already on) and the stock IAT in series. I then checked with the GS-911, the series pair did shift them temperature -30C. Next the Motronic was reset and I went out for a test ride. (LC-1 still set to 13.5.)

The result was that the bike needed little adaptation to get Open and Closed Loop fueling in sync. This produced the smoothest engine performance in all the testing I've done, and kept the point at which I've got strong roll-on throttle at about 2600 rpm.

My next test will be to remove the BoosterPlug, run with only the stock IAT and boost the fuel pressure to 50-55 psi using an external fuel pressure regulator from Aeromotive, installed in the return line to the tank. I will select and measure a pressure that boosts the fuelIng by about 12% and test ride to confirm similar results to the 30C temperature shift.

On Saturday I got around to boosting the fuel pressure to match my Wideband O2 setting of 13.8:1. I used an Aeromotive 13301 (picture below) and increased the fuel pressure from 43.5 psi (3 bar) stock to about 52 psi--install photos later. Although a BoosterPlug configured for -30C or just letting the Motronic "adapt" work, I wanted to input the actual air temperature and adaptation is a slow process.

Bottom line: My R1150RT is running its strongest and smoothest yet. The pull from about 2,000 RPM on up in 4th gear is strong. Fifth and Sixth gears are similar but a bit higher on the RPM. The bike is now stock except for the Wideband O2 and higher fuel pressure, and the Motronic has a direct connection to all sensors.

Here's why I have decided to boost the fuel pressure. BMW has done a good job designing the basic fuel map for the 1150 and I don't want to lose their design knowledge--they have a good map of RPM vs TPS (how much air is going into the engine), they just plugged in lean fuel values. Look at the fuel map for a Ducati that I linked from Brad the Bike boy's site. This is not the same map as an R1150RT but it can illustrate some points.

You can see that it has 16 RPM columns across the bottom and 16 throttle angles up the side. This table holds 256 values that specify how long, in thousandths of a second, to turn on the injectors for certain RPM and throttle positions--based on their detailed knowledge of how much air the engine draws at each point. These values are only valid for gasoline without ethanol, and for one air temperature, one barometric pressure and for 43.5 psi fuel pressure. The R1150 has sensors for actual air temperature, barometric pressure and battery voltage. Then it uses the O2 sensor in Closed Loop to determine the actual fuel pulse needed to correct for ageing and component tolerance and E10 fuel. It compares the actual pulse calculated by Closed Loop to the fuel table and comes up with a correction factor. BMW calls these correction factors: Adaptation values. From all the reading I've done there is probably no more than a 4 X 4 table of Adaptation values, maybe fewer. And these values change slowly. And while you're waiting for the slow change your bike doesn't run it's best.

The numbers in the table have been designed for a Closed Loop mixture of 14.7:1. When I fill up with E10 fuel, it would be better if every number in the table were 4% larger since ethanol is a leaner fuel than gasoline. Since I've moved the Closed Loop to 13.8, that means the numbers should all be 6% higher. So 6% for my AFR change and 4% for ethanol means I would like every number in the table to be 10% larger.

It's not really possible for us to go in and change the numbers in the table to make them 10% bigger. But you can boost fuel pressure by about 20%, and the injectors then squirt 10% more fuel using the stock map numbers. This means the fuel table now matches my wideband O2 setting of 13.8:1. And that means the Motronic doesn't have to work hard to Adapt the two to match.

The fuel pressure regulator has done away with the need for a BoosterPlug to richen the Fuel Map (The BP works by lowering the temperature the Motronic sees) and now I'm running without one.

As an example of Adaptation, I'll add some tables in the next post.

I've only had one day of running but the combination of wideband O2 and add-on fuel pressure regulator looks like a winner.

Someone asked me the other day to take a test ride with fuel pressure set to 52 psi, Motronic reset and in Open Loop mode (Wideband O2 sensor unplugged). I got out yesterday and made the run.

My report is simple, the bike runs great--smooth, good power, very responsive to throttle from 2000 RPM or so on up, even in 4th gear. A lot like the Closed Loop test rides at 52 psi and Wideband O2 set to 13.8:1. It's not really a surprise to me that it ran well in Open Loop. But I want to point out one thing: because I had the Wideband O2 installed, I knew that my setting of the fuel pressure was producing the enrichment I was looking for. Without the Wideband O2, you can crank up the fuel pressure, but you can't say for sure where you are with the enrichment.

If you go back earlier in this thread to here: Open vs Closed Loop, notice how much flatter the Closed Loop curve looks and how much tighter the histogram distribution of AFRs is in the smaller plots.

The same thing happened yesterday when I rode at 52 psi, reset Motronic, Open Loop. The range of AFRs, rather than being tightly centered on 13.8:1 where mostly around 14.3:1 and 13.3:1 (the two horizontal dashed lines in the plot below). My educated guess is that this is how the Motronic tries keep the Catalytic converter running even if the O2 sensor is dead. Normally in Closed Loop, with a stock sensor, the Motronic runs fueling a few percent above and below 14.7:1. (Snooze alert: The reason for going to the lean side of 14.7 is to allow Oxygen to recharge the Cerium in the three way converter.) So now, Open Loop the Motronic makes big moves in the fueling, still hoping to create a lean-of-14.7/rich-of-14.7 scenario. This way too rich/way to lean is a sort of limp-home-mode. (It's noteworthy that this will be how many PowerCommander and Techlusion curves would look if anyone plotted them.) I think it is very likely that this causes more fuel consumption than the Closed Loop case.

So here is the Open Loop 52 psi plot with all its "wildness".




My favorite configuration remains:
LC-1 set to 13.8:1 with Fuel Pressure boosted to 52 psi (for E10 fuel).

I've now logged about 500 miles on my add-on fuel pressure regulator (FPR) and LC-1 combo--no BoosterPlug or other changes to my stock R1150RT.

The LC-1 and FPR are tuned for a gasoline AFR of 13.8:1 using E10 fuel. The mileage includes almost 100 miles between 70 and 85 mph. Lambda on the LC-1 is now set to 0.94. And the fuel pressure regulator (FPR) is set to 52 PSI, correcting Open Loop for both the change in Lambda and the leanness of E10 fuel. As setup now, I would say that the Boxer engine is as responsive, smooth and powerful (for the bike's weight) as any engine I've owned. It's interesting to duck down below the windscreen between 60 and 80 mph in 6th gear, listening to the engine it's very comfortable at these speeds, powers and RPMs (3000-4000).

On the last series of Open Loop tests that I made, I attempted to set things up in the garage while on a conference call. Cradling the phone on my shoulder, taking the bike off the center stand and dodging some stuff piled on the floor in front of the bike led to a slow motion tip-over and a couple of deep scratches on the windscreen as it hit an adjacent bicycle. I've bought a Micro-Mesh kit and some coarser (320 & 600) sandpaper. That seems to be going pretty well. Scratches are gone, polishing it up.

When I have time, I'll take a look at all the speeds and RPMs where the Motronic is Closed Loop, at least as much as I can cover.

RB

I got out today with the GS-911 attached and a PC in the Top Case for a 100 mph run up a section of posted 50 mph highway that runs through a flat swamp nearby. I didn't get past fifth gear before running out of highway. I continue to operate at 52 psi fuel pressure and a mixture of 13.8:1 no BoosterPlug or any other modification to my '04 RT.

The idea was to see when and where the Motronic runs the Closed Loop program. I've got some charts coming but here are a few observations. Keep in mind that the max 95HP is at 7250 RPM.

--Closed Loop was operational at 100 mph (The engine seemed very smooth here)

--Closed Loop was operational in 2nd, 3rd, 4th gears at nearly 6500 RPM.

--Closed Loop was operational at 48 degrees throttle (80 degrees is wide open) going 100 mph

--In 3rd gear, while accelerating to 70 mph the Motronic was Closed Loop a lot of the time. Same in 4th gear to 90 mph.

--In 5th gear, WOT Motronic stayed mostly Open Loop from 65 mph to 100 mph. But as soon as I "relaxed" the throttle to about 3/4 open at 6400 RPM, Closed Loop kicked in. Amazing!

Given the amount of time and operating areas where the Motronic will enforce lean Closed Loop, I think it gets easier to see the advantages of mixture richening by using a Wideband O2 to shift Lambda from 1 to something less--0.94 in my case.

--At 6000 RPM & WOT the injector was on for 7.2 milliseconds. One revolution of the engine only takes 10 milliseconds at that RPM. At 7250 RPM (max horsepower) each revolution is only 8.3 mS. The injectors would be open 90% of the time!

(The air temperature was 90F today; had it been 20F the 7.2 mS injector pulse would lengthen to 8.1 mS. Were I to boost my fuel output using a -20C air-temp shifter on a 20F day, that pulse would lengthen to almost 8.6 mS. More than 100% on-time! Fuel pressure is a better method for boosting injector output (compared to IAT shifting or PCs or Techs) since it doesn't require the injector pulse to be lengthened.)

That's the raw data. I'll try and post a chart tomorrow after I've thought about it further.
RB

Roger, thank you for all the details and info you have posted in this thread. I am still trying to wrap my head around much of it, but it has certainly let some light into WTF is going on inside the Motronic brain.

BUT, making conclusions about the efficacy of IAT shifters ( or other performance mods) based on their performance at temperatures well below freezing doesn't seem reasonable.

Thanks for the kind words. You're right about the IAT shifters, they should be judged on an array of merits, with measurements. The reality is that I may have made more GS-911 and AFR measurements than others. I think that WOT At redline RPMs is going to come close to overloading the injectors. But this is off track.

Many believe that Motronic Closed Loop works for small throttle andgles and up mid RPMs. The chart I'm going to show next will demonstrate just how much of the fuel table is covered by Closed Loop operation--nearly 50 degrees throttle and up to almost 7000 RPM and at 100 mph. The Motronic is reigning almost everywhere.

Next up, the chart.

I thought some might like to see the chart but I don't have time to provide the detailed annotation yet. Briefly, the Green line has two states: Closed Loop program running is the HIGH state but forget the label on the right side of the graph, it's just used to shift the 1/0 to the top of the chart. The red and blue curves use the left axis labels.

There are 6 RPM peaks. They are gears: 1st/2nd, 2nd, 3rd/4th/5th. I'll note them on the photo later when I get time for further detail but for now the comments in the prior post apply to this chart.

In first gear, Closed Loop seems to stop at 4000 RPM. In Neutral (not on the chart) Closed Loop ends around 3000 RPM, or maybe lower.

As I mentioned in the prior post, note that in 5th gear, 6350 RPM and 45+ degrees of throttle, the Motronic goes Close Loop!

How the Motronic handles spark advance has been something of interest. When the data in the last post was collected, I also collected ignition timing data, plotted below, for reference and for those who are interested. This data is for the Motronic MA 2.4, Pink Coding Plug.

Unlike fueling which can be modified externally, spark advance is under the control of the Motronic's internal program so can't be modified without an ECU chip replacement.

The charts below show spark advance compared to RPM and to throttle angle. In the RPM chart you can see that advance is increased with RPM, reaching a maximum of about 43 degrees above 4000 RPM.

In the TPS chart though you can see that the maximum advance is only for throttle angles below 18 degrees (80 degrees is WOT), and is then reduced for wider throttle angles. From 50 degrees to wide open throttle the advance is limited to 20 degrees.

The other thing worth noting is that while the spark is advanced with RPM up to certain throttle angles, there are a lot of points scattered well off the curve. This shows that there are other factors that the Motronic uses in its timing calculations.

At 75mph in 6th gear my 1150RT feels absolutely amazing, sounds great and it makes me want to run until the tank is empty! Just a great "feel" to the motor at this speed! I don't think I ever want own a bike that isn't a BMW boxer!

Keep up the great work. I really enjoy reading through your threads, and really like to see what the ECU is doing under what conditions.

Interesting, I always knew that my bike had more power if I fed it the throttle going up a steep hill v/s cracking wide open. Thanks for all the great research!