"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
04/28/2016 at 21:48 • Filed to: None
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"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
04/28/2016 at 21:48 • Filed to: None | 0
| 5 |
So a standard O2 sensor in a car is a “narrowband” sensor, generally considered useless for tuning because of the lack of resolution. That may be true for someone trying to get perfect efficiency and power out of their engine, but what about someone who just wants to keep their ghetto-fabulous turbo setup from blowing up? Hook up a gauge to the stock narrowband sensor and if you see it go to “lean” or “rich” you know something’s fukt. Couldn’t that be adequate for a car that would just be daily driven until something more sophisticated could be put on the car?
jkm7680
> Jake - Has Bad Luck So You Don't Have To
04/28/2016 at 21:49 |
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The entire time I had my A6, there was a bad 02 sensor somewhere. I was getting like 12 mpg or something crazy, everything seemed fine.
Id say just do whatever and see what happens.
traitor joe
> Jake - Has Bad Luck So You Don't Have To
04/28/2016 at 22:01 |
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Well I don’t think it would be particularly useful, especially considering that most turbos should be run a little rich. You don’t need a wideband, but you might as well not use an O2 sensor if you plan to use a narrowband.
jimz
> Jake - Has Bad Luck So You Don't Have To
04/28/2016 at 22:02 |
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there’s a bit of a misconception about what O2 sensors do. companies marketing “Wideband” sensors claim the factory O2 sensors just “switch between rich and lean” (this is what Bosch’s aftermarket site says) which is nonsense. All O2 sensors, whether OEM, aftermarket, wideband, or whatever, measure the oxygen content of the exhaust stream. they’re passive sensors, they don’t “switch” anything. What happens on a factory calibration is that the PCM looks at the output of the sensor, and the calibration oscillates between rich and lean. the reason it does this is for the catalytic converter. see, the catalyst cleans up three trace pollutants: unburned hydrocarbons (HC/NMOG,) carbon monoxide (CO,) and oxides of nitrogen (NOx.) HC and CO are cleaned up by oxidation catalysts, meaning inside the catalytic converter the remaining hydrocarbons are oxidized (meaning oxygen is added) to H2O and CO2, and the carbon monoxide is oxidized into CO2. in the reduction catalyst, the oxides of nitrogen are reduced (meaning oxygen is stripped from) NO2/NO3 etc. into inert N2 and O2. the problem is that the oxidation catalysts work best when the engine is running lean (excess oxygen in the exhaust,) and the reduction catalyst works best when the engine is running rich (little oxygen in the exhaust.) so the engine management has to rapidly oscillate between slightly rich and slightly lean to keep the catalysts working properly.
“wideband” sensors with an appropriate PCM tune will let the engine run richer for longer at wide-open-throttle (WOT) without things freaking out. Engines always run rich at WOT to both keep temperatures down and to prevent detonation.
Danger
> Jake - Has Bad Luck So You Don't Have To
04/28/2016 at 23:05 |
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The way the narrow band works in my car is that you want it bouncing back and forth in normal driving. Lean-Rich-Lean-Rich. Then, when you floor it, you want it to stay rich while you’re in the gas. In my case the readout is 0-800, and I better have 750+ at WOT or else I’m going shopping. As you stated, it is low res and rudimentary, not as good as a wide band, but much cheaper and easy.
Michael
> Jake - Has Bad Luck So You Don't Have To
04/29/2016 at 07:33 |
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Basically you’ve said:
“I know narrowband sensors are useless for tuning, but what if I use it for tuning?”
At the end of the day, if it switches over to “lean” while you’re boosting, you’ll know that something’s wrong, but by that point you’re already 2.0-3.0 points leaner than you want to be on a safe turbo engine. The switching point is 14.7 lbs(air)/lbs(gas) and a turbo should run somewhere in the ballpark of 11.0-11.5 lbs(air)/lbs(gas)