| Author | Message | ||
     Zane |
Recently I had a problem with the voltage regulator on my '09 XT. It was allowing higher than normal voltage, upwards of 16 volts. Would that be enough to take out an O2 sensor? I've never gotten any time out of my O2 sensors. I have 28,000 miles on the bike and I'm on my 5th O2 sensor. Would higher than normal voltage take them out? Current commute is 45 minutes each way 5 times a week. | ||
| Zac4mac |
Quite possible. Too many volts is really worse than not enough. I have a single LED monitor on my Uly(tricolor, green is good) and a Drag Spec 10 segment LED voltmeter on my 1125R. Both are simple, cheap and accurate enough for a dash display. I strongly recommend either. Z | ||
| Zane |
I thought it might be an issue, but this is a subject I don't know a lot about. | ||
| Natexlh1000 |
Oxygen sensors put out a small voltage. They do not use your system power unless they are the fancy kind with the heaters. I think something bad in the gas or some other thing would take out a sensor like that. Did you bench test any of the old sensors with a volt meter and a blowtorch? You ECU could be mentally ill and lying to you. A broken wire could make your ECU blame what that wire is connected to. A loose solder connection inside the ECU can raise all kinds of hell. | ||
| Ratbuell |
The wrong threadlock on the O2 sensor threads can also kill it. They're extremely chemical-sensitive - you'll see some "sensor safe" sealers and threadlocks, O2 sensors are the primary reason for those labels. | ||
| Teeps |
Nate & Rat are correct, what they say... | ||
| Sifo |
Oxygen sensors put out a small voltage. They do not use your system power unless they are the fancy kind with the heaters. I don't think they can generate their own voltage. They are basically a variable resistor, allowing a certain voltage to pass through. Being a computer sensor, I assume they are supposed to be regulated to 5 volts on the input. That may be off if the system voltage is way high though. For what it's worth, I had a Triumph where the voltage regulator was letting full voltage of about 38 volts through. I was on a trip and wound up running that way for a few hundred miles. Fried the battery, headlight and taillight. No other problems though. As mentioned, some sealants can cause them to fail. Not only on the exhaust side, but also on the intake side. I assume the voltage issue has been fixed. If you kill another O2 sensor, check all the possible places sealant could have been used unless you know the history of work done on the bike. | ||
| Teeps |
https://en.wikipedia.org/wiki/Oxygen_sensor Zirconia sensor A planar zirconia sensor (schematic picture) The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. An output voltage of 0.2 V (200 mV) DC represents a "lean mixture" of fuel and oxygen, where the amount of oxygen entering the cylinder is sufficient to fully oxidize the carbon monoxide (CO), produced in burning the air and fuel, into carbon dioxide (CO2). An output voltage of 0.8 V (800 mV) DC represents a "rich mixture", which is high in unburned fuel and low in remaining oxygen. The ideal setpoint is approximately 0.45 V (450 mV) DC. This is where the quantities of air and fuel are in the optimal ratio, which is ~0.5% lean of the stoichiometric point, such that the exhaust output contains minimal carbon monoxide. The voltage produced by the sensor is nonlinear with respect to oxygen concentration. The sensor is most sensitive near the stoichiometric point (where λ = 1) and less sensitive when either very lean or very rich. | ||
| Sifo |
Thanks Teeps. Seems you (me) learn something new every day. | ||
| Zane |
Sifo, Yes, new voltage regulator is installed. I'm wondering if the damage was done before the new regulator was installed and this is just left over damage. PS. The bike gets new tires and brakes this week. Tires are getting pretty thin and I'm commuting about 45 miles a day now so need to have good rubber on the bike. | ||
| Screamer |
Occassional (accidental?) use of leaded gas may shorten O2 sensor life. | ||
| Zane |
I don't think its a gas issue. I only buy 91 octane and buy from 3 or 4 different gas stations. Teeps's explanation of how an O2 sensor works would seem to rule out the system voltage issue. Has anyone else gone through this many O2 sensor? With a new ECM about 1000 miles ago, new tires and brakes this week and a new O2 sensor (if it tests bad) there won't be much left of the bike to fix. | ||
| Ourdee |
As mentioned, some sealants can cause them to fail. Not only on the exhaust side, but also on the intake side. How does the anti seize used on our spark plugs effect them? | ||
| Zac4mac |
Silicone or silicon/silica will contaminate an O2 sensor. If it has silicon (Si - element) it's bad for O2 sensors. Z | ||
| Torquehd |
Anti-seize on your plugs shouldn't effect 02 sensors, or combustion, or anything else. Unless you're globbing it past the threads and onto the electrode. The ECM uses the resistance value from the spark plugs to determine the VE, or something like that. That's why you're supposed to use copper antiseize on the plugs and not the silver. IIRC. Edit. How are you testing the 02 sensors to determine that they are bad? (Message edited by torquehd on April 12, 2018) | ||
| Zane |
When I get the symptoms of a check engine light above 75 or so and it turns off when speed is reduced to about 60. I generally take it in to a dealership/or independent shop and have them read the codes. With those symptoms, it always the O2 sensor. | ||
| Teeps |
For what it's worth: My '06 Ulysses, from near new would exhibit the same behavior when ridden in anger above 75 MPH for more than a few miles. The code stored was always for the O2 sensor. Even with a new O2 sensor this would happen... when ridden as above. This never presented a problem with the engine operation and it always returned 50 MPG regardless of where or how I rode it. My thought is: that during sustained high speed running, the O2 sensor gets too hot and its output is out of the normal operating parameters. Thus the Engine Indicator comes on and the O2 DTC is stored. Slowing for a while, the sensor cools enough to return to an output in spec. | ||
| Zane |
I forgot to mention, I also see reduced mileage. Normally I get low 40's for mpg. When O2 sensor is acting up, it drops to as low as 25 mpg. It might be that it's overheating and cooking itself. I never thought about that... | ||
| Natexlh1000 |
Wow that's terrible fuel economy. Are they coming out blackened with soot? I don't think they are able to be overheated with a running engine since they show the sensors being tested in a bench vice with a propane torch. They get cherry red and don't ruin themselves. Is it possible that the rear exhaust valve guide seal is leaking oil into the hot port? Oil with Zinc is bad for the sensors. Like Rotella diesel truck oil has Zinc in there. | ||
| Zane |
Don't think it is an oil issue either. The only thing that goes in the engine/transmission is HD Syn3. | ||
| Zac4mac |
I have an 09 Uly and I don't get much more than 35mpg. That's the price we pay for 90HP out of the box instead of the 75 the earlier Thunderstorms make. | ||
| Zane |
Well, I'm not riding it very hard these days. It's become my daily rider back and forth to work. It's all interstate driving but I-10 clogs up pretty good during rush hour. It the cage it takes 60 to 70 minutes each way but on the bike in the HOV lane its just under 45. Just over 22 miles each way so you can see the traffic can be pretty fierce. | ||
| Zane |
Ok. Since my car is in the shop, I've been riding the XT back and forth to work. I'm convinced now that it is not the O2 sensor. My last fill up, I got 44.3 mpg with a three tank average of 43.8 mpg. That would never happen with a bad O2 sensor. I now have a constant check engine light from startup onward. I've noticed that the fan isn't running and the bike gets VERY hot. Sometimes in traffic to the point of going into a skip spark mode. I'm now thinking either the temperature sensor, fan motor or perhaps the exhaust valve. I did pull the air box cover off and check the solenoid. When I turn on the kill switch, twist the throttle full open and turn on the ignition switch, I can see it actuating. Still, the exhaust valve spring is really strong and I have no way of knowing if it is opening all the way or not. I don’t have a way of reading the error codes. Am I on the right track? | ||
| Sifo |
If it IS hot and it IS going into skip spark mode, I would guess the temp sensor is working. But it might be going into skip spark when it's still in the normal range of hot. If the fan isn't working, I would focus on that. | ||
| Tootal |
I would pay for the latest ECMSPY and a tether. You can check so many things in a few minutes that it's really worth it. Hit the diagnose fan button and if it doesn't run, you just found the problem. | ||
| Zane |
In stop and crawl traffic, it gets so hot I can't keep my leg near the frame for fear of getting blistered. Where can I get ESMSPY? Amazon? | ||
| Ducbsa |
You can read codes with a jumper at the diagnostic plug and count flashes at the dash. I’ m out of town,so others can give more details. | ||
| Shoggin |
The service manual has instructions to read the CL codes and how to jumper the connector. You can look at it or download it for free at Buellmods.com I would highly recommend getting the ECMDroid app from the Google Play store (for FREE) to do easy diagnostics (like test the fan) and even change the fan temp settings. You'll need a wireless connection (not a cable). but the Bluetooth dongle is cheap ($40?). I like mine from Buelltooth.com and they have lots of helpful links too. |
