2004 R1150RT Wideband O2 Sensors
I'd like to get some inputs on wide-band O2 sensors for the R1150RT.
As I understand it, under cruise conditions, constant TPS and roughly constant RPM, the Motronic 2.4 goes into Closed Loop operation, cycling between slightly rich and slightly lean with the engine running with an average AFR (air fuel ratio) of 14.7 to 1 as set by the narrow band O2 sensor and Motronic.
Digressing for a moment, in the aircraft that I flew for many years the level flight cruise setting (for a given propeller speed) was to lean the fuel flow until peak EGT (exhaust gas temperature) was achieved; or to lean to peak EGT and then richen the mixture by 25 to 50 degrees F. Peak EGT gave maximum aircraft range, and Peak EGT minus 25 degrees (or so) gave maximum speed (cruise power). (Peak EGT - 25F was also considered kinder to the engine since it was running a bit cooler.)
So if I've got it about right, when I'm cruising on an R1150, the narrow-band O2 sensor is "leaning" the engine to peak EGT and something less than best cruise power for a given condition. That being the case, I'm not surprised that the engine must be carefully tuned and balanced so that it doesn't "surge" from a bit of imbalance (one cylinder being slightly leaner than the other).
Although my particular RT seems to run well, I've got this sense that it would like to sip a bit more fuel while cruising. The BoosterPlug I installed has added some fuel to Open Loop operation but when cruising, Closed Loop O2 operation leans things right back to peak EGT--14.7:1 AFR.
One of the options for richening cruise is to keep the Motronic out of Closed Loop operation by removing or changing the CAT plug to one that tells it that there isn't a catalytic converter. But I'm not sure what AFR or EGT I'd end up with.
So like the blind squirrel looking for a nut, I've been trying to find a plug-n-play replacement for the stock narrow-band O2 sensor or a way to shift it. Today I came across the Innovate Motorsports LC-1 Wideband O2 Sensor.
As I read it, the LC-1 can be used as an Air Fuel meter or as replacement for the stock O2 sensor that can have its AFR programmed over a wide range. In this mode, one of its outputs is in the 0V to 1V range, the same as the stock narrow band O2 sensor.
I've searched this forum and others and can't find a whole lot on the LC-1. Has anyone tried this out on an R1150? What has been your experience? I'd appreciate any thoughts or comments.
Just un-plug the O2 sensor and leave code plug alone. The '04 computer isn't too sophisticated and bike will run fine with inputs from remaining sensors like air temp and oil temp affecting the fuel mixture. It would be a different story on new machines with O2 sensors after the cat.
I disconnected mine and saw a vey slight drop in fuel economy but no real improvement in performance. I might also add that I removed the cat from the stock exhaust system many moons ago so disconnecting the O2 sensor would not harm what isn't there.
I dinked around with different code plugs and decided on the green code plug so that is what I use. Green results in a slightly richer mixture and smoother performance, at least for my bike.
Which BMWs have the O2 sensors after the cat?
Originally Posted by Red100RT
I think the latter R1200's do. I looked at a 2011 R1200R that did last summer at a dealer whilst I was dreaming. Had a sensor before and after.
I think the "sensor" after the cat is the exhaust flap.
Originally Posted by Red100RT
You're probably right in that there isn't a sensor after the cat. I maybe am thinking about my Mustang. Getting old. I think the R1200R has two sensors one for each side ahead of the cat. Going to Boise and drool some more so will look again. Could have sworn I saw a sensor after the cat but probably mistaken. Sorry for bad info.
Originally Posted by kthutchinson
Thanks, I hear you. I guess a lot have taken that approach. I'd like to keep the catalytic converter. From what I've seen on this site and others: grounding pin 86 says low octane, grounding pin 87 indicates a cat converter, and 87a says its an RT-ish bike (not positive about 87a). The pink '04RT plug is what I've got.
Originally Posted by Red100RT
I'm planning to keep the converter and plug stock but shift the closed-loop mixture a bit richer. From GS-911 data I've logged while riding, the motronic spends at least half it's time closed-loop.
If you buy the LM-1 & watch the meter, you can see your bike flip flop when in closed loop (sticking probe in tailpipe), I don't think changing yoru O2 to a wideband will work with your computer, which is not programmed to use that input. The narrow band as I understand it just flip flops back & forth as the computer adjusts in closed loop. goes lean, adds a bit more fuel, goes rich, takes a bit out, over & over again, fairly quickly.
Thanks for the feedback. The flip-flopping can also be seen on the GS-911 I'm using. What have you thought of the quality of the LM-1?
Originally Posted by JStrube
I've found five different options for wideband O2 sensors with Programmable Narrow Band secondary outputs. Although the wideband primary outputs can't drive the Motronic 2.4 in the '04 RT; if properly grounded, the programmable Narrow Band outputs can.
The products are:
LM-1/2 Digital AFR Wideband Meter
LC-1 Wideband Controller Lambda Cable
MTX-L All in One AFR Gauge (Which is an LC-1 and Gauge combined)
Zt-2 Wideband AFR/Lambda Datalogger
Zt-3 Wideband AFR/Lambda
The above 5 products require 12 volts and ground, include a Bosch Wideband O2 Sensor and have Narrow Band outputs that can be programmed to switch AFR from less than 10:1 up to nearly 20:1, much more range than I'm looking for. All require a computer with Serial Port to set the switching AFR. I would start at 14.7:1 (stock setting) and step down slowly, monitoring results.
Also, the Power Commander III USB has a wideband sensor included. As everyone here knows, the PC III interfaces at both injectors, at the TPS and at the O2 sensor which gets replaced. The stock O2 is removed and the PC III, using a wideband O2, takes over the Closed Loop function from the Motronic. Their "stock" fuel maps initially set the Closed Loop AFR to 13.8:1 (compared to 14.7:1).
To keep things simple, and giving the BMW/Motronic designers due respect, I'm planning on the simplest approach, either the MXT-L or ZT-3. So far Zeitronix has been more responsive to my questions. I'm still undecided.
This may seem like a big effort for a small shift of Closed Loop AFR, but as I mentioned in the OP, reducing the Closed Loop EGT by 25 to 100 F in my flying experience has a positive effect on performance.
I took some data which is in the next post.
Last edited by Roger 04 RT; 12-01-2011 at 04:05 AM.
Yesterday I plugged in my GS-911 Diagnostic Tool, interfaced it to a small Netbook PC via Bluetooth and took some rides to gather data after the bike warmed up. On the first couple rides I lost the Bluetooth connection but the third time I got some useful data by bungy-cording the PC to the rear seat.
The bike was fully warmed up at the start. Here are the results:
Length of ride: About 15 minutes.
Course: Winding, hilly local roads.
Gears/Speeds: All six gears, many speed and gear changes, from Wide Open to Closed Throttle, up to 70 MPH
Data Points: A little over 1,000 sets of data of all functions logged by the 911 during the 15 minute ride.
RPM: 1100 to 5500;
Fuel Injection Pulse: 2ms to 3.5ms usually, peak of 4.6 ms
***45 points were 0.00ms, meaning the injectors were shut off. This occurred during abrupt deceleration.
Tank Venting: Tank venting was enabled by the Motronic about 3 minutes into the ride, then on for 5 minutes, then off for three minutes, then on again. (I included this just because I found it interesting.)
Fuel Pump: On all the time, as expected
And now the data I was looking for:
Closed Loop operation: The Motronic was Closed Loop 48% of the ride, as I mentioned, it was a winding hilly, many gear and throttle change trip. On a highway trip I would expect a higher percentage of closed loop operation, perhaps tomorrow I'll give that a try.
What this tells me is that no matter what other change you make to the motorcycle, the Motronic will be insisting on an AFR between 14.5 and 15 to 1 (approx), and be centered on a lean 14.7:1 most of the time.
I don't know what results I'll get, but it looks worth giving a programmable Narrow Band O2 sensor a try.
Last edited by Roger 04 RT; 12-01-2011 at 03:06 PM.