02 sensor

[Me-109]

Useful information on lambda sensor / O2 sensor operation:

http://home.flash.net/~lorint/lorin/fuel/lambda.htm

Have any of you actually measured output voltages from your sensors whilst connected/disconnected to see what they are actually doing whilst the engine is running?

I don't know enough about BMW mapping, especially from this era, to know how 3-D they are. A single map can still have more than one 'single line' trace and would have a ranged map depending on the inputs. The map would respond so far to a changed signal from, say, the O2 sensor without dropping onto the 'safe' mode.

Leaving the sensor connected but hanging in the breeze will render the sensor inoperative, as far as the ECU is concerned, since the temperature is not likely to get high enough to get the sensor switching electrically. The ECU will, therefore, run the engine in its richest mapping available, as though the engine is cold but without having the fast-idle enabled.

[speedmachine]

Believed me. There is a massive difference between the O2 sensor been disconnected at the exhaust and from underneath tank.
Preferred method from exhaust (for me anyway)
Might be using more fuel.
I generally get 90 to 100 miles + reserve
I have done at least four to 5000 miles with it disconnected from exhaust.
I have used it in all weather conditions.

I would rather have better midrange.
about fuel economy do not mind losing a little bit.
After all it is my toy.


if you running a chip does that automatically change O2 sensor setting.

scene to have no power. When disconnected under the tank.
But when disconnected from exhaust. It revs like mad.
When it was on the rolling road. When it got to 4000 revs.
It was like having a second power ban, you could hear the bike, picking up revs. So much faster, even, the bloke commented about it

After reading the link it seeks to me is constantly changing fuel mixture.
To meet set emission Laws and fuel consumption.
But by changing the chip and air box modifications.
R we not sending mixed messages to the ECU anyway

[sandbar]

I don't know enough about BMW mapping, especially from this era, to know how 3-D they are. A single map can still have more than one 'single line' trace and would have a ranged map depending on the inputs. The map would respond so far to a changed signal from, say, the O2 sensor without dropping onto the 'safe' mode.

Yes that makes sense. Presumably, though, when the O2 sensor is not working i.e. above reasonable throttle openings and at reasonable revs, the ecu will just be back onto its current map because it will not be getting any signal from the sensor.

I can't remember at what revs it ceases to work, but from the recesses of my mind I seem to remember something about it not working above 1/3rd throttle.

I don't like the poxy thing anyway, so I leave it disconnected under the tank. Bike runs better that way!! I have never bothered to unbolt it as well, because if it is disconnected it is not doing anything anyway!!

sandbar

[oyster]

my experience.
The 1999 came with Lenny's intake + K&N filter, no cat code plug, otherwise stock. Ran well, no surging.
I gave it a detailed full service & full oil change. Drilled the filler neck half way up. Ran much better, smoother, more responsive. 125 miles per tank. Until reserve.
Fitted a Y pipe, gas flowed all exhaust weld seams. Better performance, slightly fruitier exhaust note. 120 miles per tank.
Fitted Laser system with street silencers. MUCH louder, plus as much performance gain again as with the Y pipe. Engine definately spins up faster. 118 miles per tank.
Due to concerns over it running too weak, I removed the stock Lamda completely. This device has a built in heater, it's only effective when it's hot, and then only to make the mix lean at low revs. It can not tell the system to get more rich. I did instal a single wire Lambda, connected to an on-board fuel mix guage. These are crude and only an indication to what is going on. It shows that the mix is sort of right. Plugs read the correct colour.
So, I am confidant that with extra air entering, and the full Laser, cat plug off and O2 sensor off, it runs within the correct mix range. ON MY BIKE. This may vary on others. As has been described elsewhere, fitting the richer pressure regulator may put too much fuel through.
I have now got a Laser chip, which requires the original O2 sensor to be fitted. I will try that in a couple of months to see if there any further gains to performance.
Best gain per pound is to just fit a Y pipe.

[Me-109]

Due to concerns over it running too weak, I removed the stock Lamda completely. This device has a built in heater, it's only effective when it's hot, and then only to make the mix lean at low revs. It can not tell the system to get more rich.

Before the sensor is up to temperature, the vehicle's electronic control unit runs in what is termed 'open loop', where the ECU tosses out the information given by the O2 sensor and relies upon preset values to control the air/fuel ratio. This ends up being a slightly rich state as required when the engine is cold.

So whilst unplugged/removed it runs cold, so puts out 0V which the ECU interprets as cold so runs the engine on a rich(er) map. Surely it can then tell the system to get more rich?

[sandbar]

I think the important thing is to realise that this installation is a pretty simple and basic one. Whilst a Lambda sensor can be made to do the things that you suggest, on these bikes they are only there to reduce emissions. And they are probably used only to reduce emissions under circumstances where they are likely to be measured e.g. under the sort of conditions required to give the consumption figures for road authorites and 'showroom' figures - steady state cruising conditions. And relatively low speed ones at that!!! The US 55 mph springs to mind.

I am fairly convinced that these don't do anything at all unless the bike is being ridden pretty gently at low throttle openings. At low speeds and low revs some of the bikes - I mentioned earlier the R1150RT - are prone to surging. The general feeling is that the reason for the surging is that the system - directed by the O2 sensor - was making the engine run too lean. In a lot of cases the surging was virtually eliminated just by disconnecting the sensor. Of course BMW could not possibly admit to that and I am told that they in quite a few cases fitted the Techlusion device!

As I said - it was most predominantly an RT problem. Twin Spark improved it a bit as well. Surging was not a problem if the bike was being ridden enthusiastically.

I also recall that the Power Commander system replaces the 'narrow band' O2 sensor with a Bosch 'wide band' sensor. That can give more information and maybe that will allow an ecu plus PCII to richen as well as weaken as required.

This thread is the first time I have ever heard of an 1100S running worse just by disconnecting the O2 sensor.

sandbar

[Gromit]

As I said - it was most predominantly an RT problem. Twin Spark improved it a bit as well. Surging was not a problem if the bike was being ridden enthusiastically.

sandbar

Agreed - and both my old R1100R's were very bad whilst being ridden gently (yes - it did happen occasionally)

Removing the cream catcode plug cured the surging immediately - the bike would backfire more on the overrun, and used a bit more fuel but my God did it run better!

[speedmachine]

Reconnected O2 sensor at the tank again.
Whilst they're change pressure regulator back over to K12.
Left O2 sensor disconnected exhaust.

Bike is running good
bike was lifting front wheel, in first gear and go it to second gear
never done that before.
Only did 5 or 6 miles.

Just need to sort out ABS.
speedmachine