The CB1100 Community Forum

It turns out that I've been doing a bit of lurking here on the forum. Reading with interest the posts of others who have installed an O2 sensor eliminator. The reason for this? My CB1100 had been exhibiting fairly poor fueling characteristics at levels below approximately 3000 RPM. Each ride would end the same way: with me cruising down the street all herky jerky 'til I pulled into the driveway and shut it down. Now to be fair, while this feels like a big deal to me when I'm on the bike, I have no idea whether or not someone watching me pass by would notice this at all (or whether or not they could hear the throttle hunting in my exhaust for that matter).

At any rate, I recently went ahead and ordered an O2 sensor eliminator. Got it installed in just a few minutes. Took the bike for a quick spin around the neighborhood, just putting along nice and slow. It was like night and day. The fueling was incredibly smooth. Next I'll need to get the bike nice and warmed up and see if that makes a difference. I'm hoping that the fueling will remain smooth and steady. That's all I'm really interested in. I'm not concerned about performance gains. I'm hoping that I don't see a decrease in gas mileage.

But my question is this: why the need for this small contraption? It would seem that most here are happy with the fueling on their CBs, some reporting that it's close to perfect. Some report otherwise, a few of which have turned to solutions like the eliminator unit. Could this indicate that some of us have had O2 sensors go bad (or seriously fouled)? I'd be curious to see how my bike would respone to a replacement sensor. However that would be a far more involved not to mention a much more expensive test than just installing an eliminator plug. I guess you could say that my curiosity has only been partially satisfied.

What think ye knowledgeable forum members?

This might explain the tech behind it: https://www.hondata.com/techclosed.html

Maybe the eliminator is feeding the ECU a stable signal whereas your sensor might have been feeding it a "dirty" signal? Maybe the eliminator keeps the bike in an open loop?

Did your check engine light ever come on?

(06-15-2015, 11:41 AM)Xyzzy_imp Wrote: [ -> ]This might explain the tech behind it: https://www.hondata.com/techclosed.html

Maybe the eliminator is feeding the ECU a stable signal whereas your sensor might have been feeding it a "dirty" signal? Maybe the eliminator keeps the bike in an open loop?

The tech part makes sense to me. I'm more curious about how my bike might have evolved to the level of fluctuation that it did at lower RPMs. Could it be from all of the constant stop 'n go conditions that it is constantly exposed to during my daily commute — might that cause an increased chance of the sensor fouling? Or perhaps it was just luck of the draw and some sensors just aren't quite cutting it? No idea really. Might have to take the sensor out to inspect. The problem is I'm not exactly sure what I'd be looking for. Is there a certain look that a sensor in a good state of health should exhibit? (Say like spark plugs for example.)

Motogeezer: no, I've never seen the check engine light come on.

(06-15-2015, 01:26 PM)Guth_imp Wrote: [ -> ]

(06-15-2015, 11:41 AM)Xyzzy_imp Wrote: [ -> ]This might explain the tech behind it: https://www.hondata.com/techclosed.html

Maybe the eliminator is feeding the ECU a stable signal whereas your sensor might have been feeding it a "dirty" signal? Maybe the eliminator keeps the bike in an open loop?

The tech part makes sense to me. I'm more curious about how my bike might have evolved to the level of fluctuation that it did at lower RPMs. Could it be from all of the constant stop 'n go conditions that it is constantly exposed to during my daily commute — might that cause an increased chance of the sensor fouling? Or perhaps it was just luck of the draw and some sensors just aren't quite cutting it? No idea really. Might have to take the sensor out to inspect. The problem is I'm not exactly sure what I'd be looking for. Is there a certain look that a sensor in a good state of health should exhibit? (Say like spark plugs for example.)

Motogeezer: no, I've never seen the check engine light come on.

The service manual mentions that a special tool is needed to remove the sensor. There is no mention of how to test the sensor to see if it is defective. Even the Common Service Manual doesn't mention any troubleshooting tips.

It would be interesting to hook up a DVM to the sensor (while the engine is running) and log the values to see what kind of signal the sensor is sending to the ECU. I have no idea how to data log something like that. Maybe Honda views the sensor as a "non-servicable" part?

Code:
Tag Part # Description Price Our Price
14 36531-MGC-N21 SENSOR, OXYGEN $195.18 $171.76

I had my sensor disconnected when I first put on the Yosh, the check engine light would come on but the motor didn't run any differently. I imagine the computer went into default mode as far as O2 input goes. To make the light go off, I hooked the sensor back up and zip tied it in the breeze til the eliminator arrived. Never had any running issues either way.

There is technical info on O2 sensor operation all over the internet. In general you need a scan too to check one. A DVM can be used, but may not respond fast enough to see the signal change.

An analog meter would show it, but one site said use a DMM with a min. of 10Meg ohm. to avoid damage to the sensor. Analog meters are usually around 20K per volt.

Disclaimer. I have never tried to meter an O2 sensor and do not have any scan tools.

Here is the information from Redline Superbikes, the Ebay source many have used for the O2 Sensor Eliminators:
(Note: I have yet to install mine as the normal TPS reset procedure seems to be all my bike needs to run smoothly.)

How Does An O2 Eliminator Work

The O2 sensor which is installed in the stock exhaust systems of motorcycles are used by the Manufacturer to adjust the fuelling in order to pass the emission tests for street homologation.

This is done only in a very limited RPM range under certain load situations. The intention behind it is not to improve the performance of the machine. It's aimed to reduce the emissions of the engine in the specific RPM/Load situations which are tested during the homologation process.

This can result in delayed throttle response or unsteady power delivery. If you replace your silencer or exhaust system or fuelling, it's suggested to remove the installed sensor and replace it with this eliminator.

The eliminator simulates the signal given from the O2 sensor under optimal A/F ratio conditions. This allows the bike to run under best performance conditions.

If you install an aftermarket exhaust, remove the catalyst, install a power commander or perform similar modifications we strongly suggest installation of an O2 sensor eliminator for the best performance of your machine.

Why the need? Primarily fuel control. The CB's computer (powertrain control module (PCM)) is programmed at the factory to deliver the proper air/fuel ratio for the operating conditions. This is the programming. Programming assumes everything is in proper operating condition. As the CB ages, things go askew. Garbage in results in garbage out. The CB no longer delivers the proper air/fuel ratio for the operating conditions. This is where the oxygen sensor (O2S/HO2S) comes into play. The HO2S is calibrated for the air/fuel ratio of the engine it's designed for - generiocally - 14.7:1 (stoichiometry/lambda). Median HO2S voltage - generically speaking - 450mV equates to 14.7:1. As defects appear they affect the HO2S' median voltage. The PCM will deviate from the programmed fuel injector on-time to compensate bringing the HO2S back to it's designated median voltage in turn bringing the air/fuel mixture back to it's designed ratio.


Let's say the fuel pump weakens and fuel pressure drops. This will result in a biased lean air/fuel ratio. A leaner than desired air/fuel ratio will skew the median HO2S voltage low. The PCM responds to a low median HO2S voltage by increasing the fuel injector on-time from it's original programming. Adaptive fuel strategy, integrator/block-learn, short-term/long-term fuel trim. This is what makes modern vehicles so great. Why folks feel the need to screw this up by removing the HO2S is beyond me.

The PCM is supposed to monitor HO2S performance and illuminate the malfunction indicator light (MIL, check engine) when there's a problem. This doesn't always happen. Japanese manufacturers are hesitant to turn on warning lights. Warning lights upset customers.

HO2S' can be tested using a digital storage oscilloscope (DSO). Artificially manipulate the a/f ratio full rich (propane) and measure maximum HO2S voltage. Artificially manipulate the a/f ratio full lean (vacuum leak) and measure minimum HO2S voltage. Snap the accelerator engaging acceleration enrichment and measure how long it takes the HO2S to transition from lean to rich. Min, max, rate of change. Minimum spec is 0-170mV. Maximum spec is 800-1000mV. Rate of change (170mV - 800mV) should be less than 100mS.

TMI

(06-15-2015, 11:09 PM)immgunn_imp Wrote: [ -> ]Why the need? Primarily fuel control. The CB's computer (powertrain control module (PCM)) is programmed at the factory to deliver the proper air/fuel ratio for the operating conditions. This is the programming. Programming assumes everything is in proper operating condition. As the CB ages, things go askew. Garbage in results in garbage out. The CB no longer delivers the proper air/fuel ratio for the operating conditions. This is where the oxygen sensor (O2S/HO2S) comes into play. The HO2S is calibrated for the air/fuel ratio of the engine it's designed for - generiocally - 14.7:1 (stoichiometry/lambda). Median HO2S voltage - generically speaking - 450mV equates to 14.7:1. As defects appear they affect the HO2S' median voltage. The PCM will deviate from the programmed fuel injector on-time to compensate bringing the HO2S back to it's designated median voltage in turn bringing the air/fuel mixture back to it's designed ratio.


Let's say the fuel pump weakens and fuel pressure drops. This will result in a biased lean air/fuel ratio. A leaner than desired air/fuel ratio will skew the median HO2S voltage low. The PCM responds to a low median HO2S voltage by increasing the fuel injector on-time from it's original programming. Adaptive fuel strategy, integrator/block-learn, short-term/long-term fuel trim. This is what makes modern vehicles so great. Why folks feel the need to screw this up by removing the HO2S is beyond me.

The PCM is supposed to monitor HO2S performance and illuminate the malfunction indicator light (MIL, check engine) when there's a problem. This doesn't always happen. Japanese manufacturers are hesitant to turn on warning lights. Warning lights upset customers.

HO2S' can be tested using a digital storage oscilloscope (DSO). Artificially manipulate the a/f ratio full rich (propane) and measure maximum HO2S voltage. Artificially manipulate the a/f ratio full lean (vacuum leak) and measure minimum HO2S voltage. Snap the accelerator engaging acceleration enrichment and measure how long it takes the HO2S to transition from lean to rich. Min, max, rate of change. Minimum spec is 0-170mV. Maximum spec is 800-1000mV. Rate of change (170mV - 800mV) should be less than 100mS.

TMI

I appreciate this information, but if you read the O.P.'s original question, it is not "why we need the O2 Lambda Sensor?", it is really "why do some bikes run better with the Sensor Eliminator?".

Now, I am no electronics expert, but the information provided by Redline Superbikes seems to answer this. It may be somewhat self-serving information, but it seems to make sense.