Member Contributer CharlesW Posted August 5, 2012 Member Contributer Share Posted August 5, 2012 Having read a few posts about O2 sensor eliminator failure, I have a question. If they do fail, (Dynomax or Radio Shack Resistors), will you get a FI light telling you something is not right?? My question pertains to a 2004, but I would think it would apply to any year with factory O2 sensors that have been eliminated. Quote Link to comment Share on other sites More sharing options...
Member Contributer johnmark101 Posted August 5, 2012 Member Contributer Share Posted August 5, 2012 Interesting question. I have not heard of any failure of the 330 ohm resistors. Used the ones from Radio Shack on my bike and no issues in many years of riding. Quote Link to comment Share on other sites More sharing options...
Member Contributer CharlesW Posted August 5, 2012 Author Member Contributer Share Posted August 5, 2012 Granted, most of the failures I have read about have been the Dynojet "optimizers". The Radio Shack resistor failure I remember was possibly because of using too small of a wattage resistor. Evidently the 330 ohm resistors are available in various wattages. I happen to have the Dynojet eliminators and have no problem at this time, but...... I would still like to know what if any indication you get if the modification does quit working. Quote Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted August 6, 2012 Member Contributer Share Posted August 6, 2012 Well, the O2 eliminator resistor is connected to the heater circuit. The resistor is basically fooling the ECU into thinking the O2 sensor is not up to temperature, so it never goes into closed loop mode. if the resistor failed and went open circuit you would get an OS sensor heater error (error 23/24). If the resistor failed and shorted, that would trip the ECU fuse. If the resistor failed to the point where the ECU thought the O2 sensor was heated up, you would get an O2 sensor error (error 21/22) when the bike went into closed loop as it would see an open circuit. The most likely scenario would be getting an error code 23 or 24 if the resistor failed. Quote Link to comment Share on other sites More sharing options...
Member Contributer CharlesW Posted August 6, 2012 Author Member Contributer Share Posted August 6, 2012 Well, the O2 eliminator resistor is connected to the heater circuit. The resistor is basically fooling the ECU into thinking the O2 sensor is not up to temperature, so it never goes into closed loop mode. if the resistor failed and went open circuit you would get an OS sensor heater error (error 23/24). If the resistor failed and shorted, that would trip the ECU fuse. If the resistor failed to the point where the ECU thought the O2 sensor was heated up, you would get an O2 sensor error (error 21/22) when the bike went into closed loop as it would see an open circuit. The most likely scenario would be getting an error code 23 or 24 if the resistor failed. And that's the information I was looking for! Thanks! The comments about the Dynojet Optimizers being prone to failure were making me somewhat paranoid. At least if they fail I will know it. Quote Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted August 6, 2012 Member Contributer Share Posted August 6, 2012 The comments about the Dynojet Optimizers being prone to failure were making me somewhat paranoid. Yes, the term "optimisers" is not exactly accurate. They renamed them because many newer model bikes don't fall for the resistor-in-the-heater-circuit trick. So, Dynojet have two products - one is the resistor, and the other is an actual optimiser but they call them both the same thing. What the real optimisers do is take the O2 sensor signal and mess with it, so that when the bike's ECU thinks it's hitting 14.7 AFR it's actually hitting about 13.6 AFR. I believe they're simple voltage dividers which convert a signal of 0.75 volts from the O2 sensor into about 0.500 volts (which denotes 14.7 AFR). So the bike ECU sees 0.5 volts but in order to see that number it actually has to richen up the mixture so that it's *actually* creating a 0.75 volt reading from the O2 sensor. They do not offer this product for the VFR800 because the ECU in our bikes is so brain-dead it's easy to fool. In fact I think all the Honda systems are still dumb as dog crap. If you go to the Powercommander website, install instructions for Honda bikes will say "plug in O2 optimiser, you can then leave the O2 sensor disconnected or remove it from the exhaust". However for a modern Yamaha bike, the install instructions will say "plug the optimiser in-line between the O2 sensor and the ECU". Subtle difference, no? For those bikes, the Powercommander instructions will also say stuff like "don't tune any cells between 0 and 15 percent throttle and 0-6,000rpm". However, since the Honda is, as I say, brain-dead you are actually able to tune the Powercommander in those ranges. So I guess the Honda stupidity kind of makes it easier to tweak the bike... There are more advanced systems on the market (not from Dynojet) which replace the narrowband O2 sensor with a wideband one, but include a calculated narrowband voltage output. These are nifty for engine tuning whilst keeping the closed loop capabilities of the stock ECU in place. Does that make sense? Quote Link to comment Share on other sites More sharing options...
Member Contributer CharlesW Posted August 6, 2012 Author Member Contributer Share Posted August 6, 2012 The comments about the Dynojet Optimizers being prone to failure were making me somewhat paranoid. Yes, the term "optimisers" is not exactly accurate. They renamed them because many newer model bikes don't fall for the resistor-in-the-heater-circuit trick. So, Dynojet have two products - one is the resistor, and the other is an actual optimiser but they call them both the same thing. What the real optimisers do is take the O2 sensor signal and mess with it, so that when the bike's ECU thinks it's hitting 14.7 AFR it's actually hitting about 13.6 AFR. I believe they're simple voltage dividers which convert a signal of 0.75 volts from the O2 sensor into about 0.500 volts (which denotes 14.7 AFR). So the bike ECU sees 0.5 volts but in order to see that number it actually has to richen up the mixture so that it's *actually* creating a 0.75 volt reading from the O2 sensor. They do not offer this product for the VFR800 because the ECU in our bikes is so brain-dead it's easy to fool. In fact I think all the Honda systems are still dumb as dog crap. There are more advanced systems on the market (not from Dynojet) which replace the narrowband O2 sensor with a wideband one, but include a calculated narrowband voltage output. These are nifty for engine tuning whilst keeping the closed loop capabilities of the stock ECU in place. Does that make sense? I'm sure it does to the more technically oriented members. Me, I just buy the plug-in stuff and hope I don't mess up plugging it in. That's the reason I went the Dynojet route for my O2 eliminators. Quote Link to comment Share on other sites More sharing options...
Guest Michelangelo Posted September 13, 2012 Share Posted September 13, 2012 Is there any benefit to doing the resistor or O2 bypass mod on a stock bike? Quote Link to comment Share on other sites More sharing options...
ciprinakos Posted September 14, 2012 Share Posted September 14, 2012 See here: Quote Link to comment Share on other sites More sharing options...
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