Novakaine Posted December 8, 2004 Share Posted December 8, 2004 So, I tested my o2 sensor...i think. Here is what i did: This is a three wire sensor, two white and one black. The two white wires i assume are for the heating element, and the one black wire is the O2 sensor...is that right? So I splice my multimeter positive to the black wire, and chassi grounded the negative. The voltage fluctuated between .15 volts to .8 volts and crossed .5 volts 4 or 5 times every 10 seconds. Is it time to replace the O2 sensor. Also, I am thinking the 02 sensor is bad because i get about 19 - 20 mpg, on average, but i do drive around 75 mph. And also, since i don't have a tach, i don't know the rpm, but curing idle the engine sounds like it gets a little low, and is about to stall, but then it revs a little higher and all is good. That only happens maybe 3 or 4 times, every 10 minutes. What do you guys think? Quote Link to comment Share on other sites More sharing options...
friendly_jacek Posted December 8, 2004 Share Posted December 8, 2004 So, I tested my o2 sensor...i think. Here is what i did: This is a three wire sensor, two white and one black. The two white wires i assume are for the heating element, and the one black wire is the O2 sensor...is that right? So I splice my multimeter positive to the black wire, and chassi grounded the negative. The voltage fluctuated between .15 volts to .8 volts and crossed .5 volts 4 or 5 times every 10 seconds. Is it time to replace the O2 sensor. Also, I am thinking the 02 sensor is bad because i get about 19 - 20 mpg, on average, but i do drive around 75 mph. And also, since i don't have a tach, i don't know the rpm, but curing idle the engine sounds like it gets a little low, and is about to stall, but then it revs a little higher and all is good. That only happens maybe 3 or 4 times, every 10 minutes. What do you guys think? The voltage looks good for the traditional (non-wideband) sensor in closed feedback. At least it sounds similar to what I have seen on my OBD-2 reader. This is a front sensor, right? It would be abnormal in after-cat sensor in a warmed-up car though. Quote Link to comment Share on other sites More sharing options...
Novakaine Posted December 8, 2004 Author Share Posted December 8, 2004 The voltage looks good for the traditional (non-wideband) sensor in closed feedback. At least it sounds similar to what I have seen on my OBD-2 reader. This is a front sensor, right? It would be abnormal in after-cat sensor in a warmed-up car though. yup, this is the front sensor. If it is a good sensor, then my mileage is pretty crappy. Why do you think? Anything else i can check/do for better mileage? Quote Link to comment Share on other sites More sharing options...
frag Posted December 9, 2004 Share Posted December 9, 2004 According to Chilton's, if the sensor's voltage crosses .5 volt less than 5 times in 10 seconds, the sensor may be faulty. I think 4 or five time like you write is at the very least a little borderline. A few of us on this board (Commuter is part of those I think) have found out that a «lazy» O2S will degrade fuel mileage without tripping a CEL. If your front O2 sensor has never been replaced, maybe you could replace it and see what happens. Quote Link to comment Share on other sites More sharing options...
Tiny Clark Posted December 9, 2004 Share Posted December 9, 2004 If it has never been replaced, then do it. O2 sensors don't last forever.http://www.oxygensensors.com/ You can buy the 7/8" socket for it at Autozone, Advance, etc... Quote Link to comment Share on other sites More sharing options...
shimonmor Posted December 9, 2004 Share Posted December 9, 2004 I replaced my front O2 sensor at 100k miles and I never had a CEL for it and I noticed a marked improvement in engine idleing and fuel economy. If you have around 100k miles...replace it! Good preventative maintenance. Quote Link to comment Share on other sites More sharing options...
Novakaine Posted December 9, 2004 Author Share Posted December 9, 2004 I replaced my front O2 sensor at 100k miles and I never had a CEL for it and I noticed a marked improvement in engine idleing and fuel economy. If you have around 100k miles...replace it! Good preventative maintenance. Thanks guys, I think I will replace it soon. I will let you all know if there was any difference. Quote Link to comment Share on other sites More sharing options...
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