O2 Sensor bypass

SupraSabre · Mar 24, 2012

The are o2 sensor by pass plugs being sold on ebay, will they do the job?

ebay o2 sensors

He doesn't show the back, but all it is, is the two wires have been connected together. I would have thought some resistor would be required, not just shorting out the two wires!

Stump · Mar 24, 2012

Re: o2 Sensor by pass

Why would you ever want to disable the main fuel metering device of the fuel injection system?

Tom Mac 04a · Mar 24, 2012

Re: o2 Sensor by pass

SupraSabre said:
but all it is, is the two wires have been connected together.

The rubber wire could be shrink tube ... maybe a resistor is in the shrink tube which connects lead to lead

It would really need just the blue and white wires as black are common grnd

* Don't know how well this will work on the ST's Some O2 units require a lot more of a curcuit.

sennister · Mar 24, 2012

Re: o2 Sensor by pass

Stump said:
Why would you ever want to disable the main fuel metering device of the fuel injection system?

I have seen this before when people remove the cats with a custom exhaust. They use O2 simulators to trick the downstream O2 sensors into thinking the cats are there and are working right.

On the ST though I think there are just the upstream o2 sensors AFAIK. So I don't see the benefit in removing them. It isn't because they are removing the cats.

rrboomer · Mar 24, 2012

Re: o2 Sensor by pass

Hello ! I may be missing something here. The o2 is an electrical generator. The flow of exhaust induces a small flow of current back to the ecu. This is a check of how well the system is doing. Unless there is a place to pick up juice how can the eliminator work ? I guess they tap the preheat wire . I thought they were a timed or operating temp turned off . That woud be like running glow plugs 100% of the time if the 02 heaters worked all the time. What give?rr

v8-7 · Mar 24, 2012

Re: o2 Sensor by pass

The O2 narrowband sensors send a signal, usually between 0-1.2?v to the ECU so the ecu can trim the fuel mixture to the proper
conditions ( temp, air density, load ect.) .

The eliminators take the 12v line and using a resistor reduce it to what the ecu expects to see for a normal situation such as .5v .

As Stump said , why would anyone want to this ?

Based on manifold vacuum, throttle position , intake air temp, sometimes air flow , RPM etc , the ECU continually leans or
enrichens the fuel mixture for either the best mpg. lowest emissions or maximum power depending on the tune. Usually all three depending on driving conditions

On our bike, It will sense when you are cruising and seek Stoic for maximum MPG and/or minimize emissions , under acceleration it will maximize power

bypassing this sensor will make the bike run worse, cause higher emissions and get worse mpg's .

Talonboy · Mar 24, 2012

Re: o2 Sensor by pass

v8-7 said:
The O2 narrowband sensors send a signal, usually between 0-1.2?v to the ECU so the ecu can trim the fuel mixture to the proper
conditions ( temp, air density, load ect.) .

The eliminators take the 12v line and using a resistor reduce it to what the ecu expects to see for a normal situation such as .5v .

As Stump said , why would anyone want to this ?

Based on manifold vacuum, throttle position , intake air temp, sometimes air flow , RPM etc , the ECU continually leans or
enrichens the fuel mixture for either the best mpg. lowest emissions or maximum power depending on the tune. Usually all three depending on driving conditions

On our bike, It will sense when you are cruising and seek Stoic for maximum MPG and/or minimize emissions , under acceleration it will maximize power

bypassing this sensor will make the bike run worse, cause higher emissions and get worse mpg's .

Like you said, eliminating the o2 sensors and replacing with a resistor, will fool the ECU to think the o2 sensors are there and working fine. But, the stock narrow-band o2 sensors are only used in closed loop operation i.e. lower rpm and throttle positions. At higher rpm and throttle positions, the bike is in open loop, and does not use the o2 sensors. Bypassing the o2 sensors will not effect how the bike runs in open loop. The bike uses the 02 sensors to pass emissions, not make it run better. If you bypass the o2 sensors, you will create more emissions, and get worse fuel mileage; but you most likely will make the bike run better in closed loop.

v8-7 · Mar 24, 2012

Re: o2 Sensor by pass

Even if you had a way to change the air/fuel ratio , wouldn't it be better to have feedback from an O2 sensor ?

It can also be done with an exhaust gas temperature sensor, but it's not as accurate or nearly as fast .

I don't know how the power commander works. Do they just dial in fuel and/or timing based on preset maps using the other sensors ?

SupraSabre · Mar 24, 2012

Re: o2 Sensor by pass

BTW, I stand corrected, there is a resistor in between the two connectors.

1. The reason I was looking to try these was I have had people ride behind me telling me they can smell my exhaust and it smells rich.
2. With 143K miles on them I wonder how much they are working still.
3. I have the TurboTom Fuel regulator, so I was thinking it might run better without the o2 sensors.

I'm really not up on all the electronics that make these bike work, but experimenting a little is something I don't mind trying once in a while.

dkwflight · May 18, 2014

Re: o2 Sensor by pass

Hi
I just installed O2 sensor eliminators on my '06 st1300
The bike seems to run fine but the F1 light still comes on.
The eliminators are equipped with resistors bought from the UK on E bay. Good service from that guy

Any ideas ?

Dennis

dkwflight · May 18, 2014

Re: o2 Sensor by pass

[QUOTE;1751785]I am not sure how these would benefit a standard ST. I fitted a bazazz unit, which includes O2 eliminators. Everything worked flawless no F1 lights or anything. Really brought the bike alive,especially at the lower end. Can also run 1 of 2 programs.[/QUOTE]

where can a Bazazz? unit be purchased.
I had a bad sensor because of a accident and the bike laid on it side for a while.
When I started the bike after the accident a lot of oil burned off. I suspect the oil contaminated the O2 sensor on the left side.

dkwflight · May 18, 2014

Re: o2 Sensor by pass

Hi I found the Bazazz unit and instructions from the mfg.
I went with the simple O2 eliminator (plug with a resistor) because of price compared to replacing the O2 sensors.
Just looking for a cheap way out.

dkwflight · May 18, 2014

Re: o2 Sensor by pass

Hi
The E bay O2 sensor eliminator has a resistor built in.
I chose those as an alternative to replacing the O2 sensors because of cost.
The only issue I have is the FI light stays on. The bike runs great.

ST Gui · May 18, 2014

I'm not crazy about increasing emissions but understand wanting to avoid a big expense. Does the resulting increase effect the life of the cats? What is their life expectancy and are they pretty much ignored?

dkwflight · May 18, 2014

ST Gui said:
I'm not crazy about increasing emissions but understand wanting to avoid a big expense. Does the resulting increase effect the life of the cats? What is their life expectancy and are they pretty much ignored?

It is my understanding of the operation of the cat converters that normal amounts of fuel being burned will not hurt them
I had a truck that got to running very rich and the cats plugged.
My Honda ST1300 actually have rubber valves in the heads working with the crankcase pulses pushing extra air into the exhaust to help the cats work.
I am not worried about the cat converters. If they get plugged I will break the cats out.
Mean while the bike shows no signs of rich running.

Blrfl · May 18, 2014

dkwflight said:
The only issue I have is the FI light stays on. The bike runs great.

The FI light is on because whatever you installed in place of the oxygen sensors doesn't look to the ECM like working oxygen sensors. Depending on what you replaced, the ECM should have stored any or all of codes 21 through 24. This puts the system into open-loop mode, where fueling is done on a best-guess basis using nominal, but not optimal, values.

dkwflight said:
It is my understanding of the operation of the cat converters that normal amounts of fuel being burned will not hurt them

The open-loop maps shouldn't damage he converters if everything else in the system works properly. If something else goes wrong and the ECM can't get feedback on how its choices for fueling are doing, it could run rich.

My Honda ST1300 actually have rubber valves in the heads working with the crankcase pulses pushing extra air into the exhaust to help the cats work.

That's the PAIR system. The air is there to burn any fuel in the exhaust stream before it reaches the converters and heats up the catalyst by burning there.

--Mark

BD's Cycles · Nov 16, 2018

I just spoke to Ivan (the carb and FI guru). He says that by installing a simple jumper on the clutch switch, the bike's terrible "on/off" throttle abruptness should be cured.
http://www.ivansperformanceproducts.com/fce.htm

He also recommended some 02 eliminators, which I just ordered off ebay, for $25. He claims the factory fueling on the bike is good, and that by doing this mod, it will emimate the irritating "surging" at highway speeds.

I don't care about the FI light staying on (if it does) or reduced MPG. I want the bike to be more ride-able, the closed throttle abruptness and the highway surging are terrible on this bike.

Mellow · Nov 16, 2018

BD's Cycles said:
I just spoke to Ivan (the carb and FI guru). He says that by installing a simple jumper on the clutch switch, the bike's terrible "on/off" throttle abruptness should be cured.
http://www.ivansperformanceproducts.com/fce.htm

He also recommended some 02 eliminators, which I just ordered off ebay, for $25. He claims the factory fueling on the bike is good, and that by doing this mod, it will emimate the irritating "surging" at highway speeds.

I don't care about the FI light staying on (if it does) or reduced MPG. I want the bike to be more ride-able, the closed throttle abruptness and the highway surging are terrible on this bike.

The FCE results are mixed to say the least.
https://www.st-owners.com/forums/threads/fce-fuel-cut-eliminator-for-st1300-on-off-throttle-issue-resolved.80672/

wjbertrand · Nov 16, 2018

The O2 sensor bypass is just a jumper, with proper resistance, across the heater wires. The ST's diagnostics aren't very advanced and the ECM is only monitoring the filament of the sensor's heater. When I was trouble shooting my ST jumping these two terminal (of the four in the connector) with eliminators kept the FI light off and didn't cause a error code to be set.

SupraSabre · Nov 16, 2018

Funny, I started this thread, but never installed those jumpers... They are in my parts bin...someplace!

O2 Sensor bypass

SupraSabre

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