Disconnected O2 sensors
 

So now that I have a custom mapped Power Commander my O2 sensors are disconnected meaning my bike is always running in an open loop. What are the full ramifications of this?

I'm guessing it will throw a fault of some kind but I am more interested in what the bike doesn't do anymore without the sensors. Any real technical guys want to explain all this to the engine management challenged?

JT

Not sure about the fault code, but I would think you disconnect the O2 sensor because the PC is now controlling the fueling and any input from the O2 would / could throw the PC map off.

Yes, I know why they are disconnected. I was just curious as to what all the ramifications are. Like, does this affect the engine at altitude? Does it affect knock sensors? Will it affect fuel mileage? What all does the computer use the O2 input for?

It's gonna affect all of that, except maybe the altitude operation. Run it richer and the knock sensors won't usually matter. Run it richer and you mileage goes down. The O2 sensor only gives feedback on how much O2 is in the exhaust stream. Less O2 means richer, more O2 is more lean. For the altitude, I think there is a pressure sensor in the ECU to take care of that. Aside from all that, it's interesting that nobody has used the O2 sensors to tune AFR. Monitor RPM and skew the O2 sensor reading rich or lean at whatever RPM to adjust the final AFR. The ECU already does this by itself but tied to a specific voltage reading from the O2 sensor to provide 14.7:1 .

An O2 sensor measures the amount of oxygen in the exhaust gas.
They provide two things;

1. The means to maintain a correct air/fuel ratio
2. Help reduce emissions by their function

The first chore has been taken over by your PC3.
The second chore is.......no more.
Previously, if the sensor picked up a rich mixture (unburned hydro-carbons), it would adjust the mixture to "add" more oxygen to more fully burn the mixture.
I don't know how many miles you've ridden since the PC3 installation, but it likely would have thrown a code quickly if there was an issue.
No code, runs good, don't worry, be happy.

Oh, and your fuel mileage will likely drop a bit. Win-win.
Drop dead algore..............

JT, did they disconnect the sensors and leave them open or did they install a dummy load on each one? There would be a small cap over the plug on the ECU side.

Many people on many forums and in many garages have tried it for many years.
Usually guys who have never looked closely at an actual normal O2 sensor signal. Doesn't work well.

Though an analog signal, the O2 sensor's output is a rough approximation of a square wave. i.e. except for a brief transition period (steep rise/fall times) the signal tends to hover near max or min (a bit like an injector signal, or pwm pulsetrain) As such, biasing it a bit one way or the other, as one would a temp sensor, has little, and not well predictable, effect on the output. i.e. it tweaks the waveform primarily in the region it spends little time, and does nothing for the rest of the time (can't raise the ceiling, nor lower the floor)

Anyway, it's an idea that makes sense at a block diagram level, and one I ignorantly tried to play with on an old 80s audi too, but eventually, I realized what was happening. The idea comes up a lot though - it's just so much easier to spoof any number of other sensors, especially temp, or where they exist, discrete pressure (often in ECU, so not doable)

hth
roger

I'm surprised it wouldn't be easier considering bad O2 sensors that bias themselves rich or lean do it so well.
Can we buy bad factory O2 sensors right off the line that tested with a lean bias? Wouldn't THAT make algore happy.

Roger, Thoughts on the Auto tune feature on a Power Commander V.

Great question, I was about to ask the same thing.

Hi guys,

PC III:

Disconnecting the O2 sensors, the BMS-K goes to lambda 1 (AFR 14) and there is no error code (lamp) shown in the dashboard.


RB III:

eliminators should be used here.

http://img864.imageshack.us/img864/6...100sbirc99.jpg


http://img828.imageshack.us/img828/644/r1200rkurt.jpg
http://img851.imageshack.us/img851/4833/r1200slarsi.jpg
http://img96.imageshack.us/img96/4299/r1200sldkla1.jpg
http://img190.imageshack.us/img190/1140/r1200s0677.jpg

Thanks Fralind, what engine improvements did you do to the 1100 to get this much hp?
What are the engine differences in the four 1200 runs?

1100, etc. With Cruiser Crankshaft (1170 cc) Machined cylinder heads, 1200 S valves, camshafts, Staitune usw.
Full House. ;)



The R 1200 R
Big Bore kit, complete Akra, PCIII, Boxer Burner, camshafts,


The R 1200 S

Different configurations

Akras complete, Q-quad exhaust manifold with HPE
PC III, Rapidebike 3, Boxer Burner
Woessner pistons with longer connecting rods

No cap. As a matter of fact about the only thing I wasnt really happy with the instalation was that they were just zip-tied open to the elements. I have since covered them with electrical tape and ziptied them a little closer so they dont flap around.

Fralind, what's the dyno type and software.

Amerschläger P4

Amerschläger p4

Wow! So you have a 1100 that makes near the same power as the 1200's? Those HP numbers are DIN, not SAE correct? How about torque curves? Very cool!

Specifications in DIN HP and torque curves (Nm) are the bottom lines with the points.


http://www.imgbox.de/users/Larsi/QD.jpg

Ah-ha but you still didn't fix the 4k-5k flat spot. :D