O2 Sensor?
in [Toyota]
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From: Sarah Houston on 20 Dec 2008 01:19 "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : > > "Sarah Houston" <SHoust(a)pndfnospam.com> wrote in message > news:Xns9B74A7A9D94D5SntzldfrdSntzldfrdco(a)216.196.97.142... >> "larry moe 'n curly" <larrymoencurly(a)my-deja.com> wrote : >> >>> Sarah Houston wrote: >>> >>>> After doing some extensive reading, it began to come clear how the >>>> O2 Sensor performance could be off, yet not be able to see any >>>> symptoms (other than lower gas mileage) with the tools I was >>>> using. It turns >> out >>>> that the O2 swing cycle shown in the photographs is the swing time >>>> of the overall system and not just the O2 sensor itself. To really >> examine >>>> the performance the O2 sensor, for example to determine if it was >>>> developing a lean or rich offset, one would have to use a digital >> volt >>>> meter with an averaging feature connected directly to the sensor >>>> and look for the 450mV centerline signal in a known, properly >>>> performing system centered at the 50% duty cycle. >>> >>> Are there digital voltage meters that don't average semi-fast >>> signals? I think for testing O2 sensors, a meter with a >>> fast-reacting bar graph would be better. >>> >>>> To measure responsiveness, one would have to use a laboratory >>>> scope >>> >>> Why? It's just a low frequency signal that any regular scope, or >>> even a cheapo handheld 1 MHz scope/DVM can display. >>> >>> Do any owner's manuals mention a replacement interval for the O2 >>> sensors, that is, for vehicles made since the mid-1980s? >>> >> >> I googled and found: >> >> http://www.autohausaz.com/html/emissions-oxygen_sensors.html >> >> Oxygen Sensors Don't Last Forever >> Here's What Happens As They Age >> >> As an oxygen sensor ages, contaminants from normal combustion and >> oil ash accumulate on the sensing element. This reduces the sensor's >> ability to respond quickly to changes in the air/fuel mixture. The >> sensor slows down and becomes "sluggish". >> >> At the same time, the sensor's output voltage may not be as high as >> it once was, giving the false impression that the air/fuel mixture >> is leaner than it actually is. The result can be a >> richer-than-normal air/fuel mixture under various operating >> conditions that causes fuel consumption and emissions to rise. >> >> The problem may not be noticed right away because the change in >> performance occurs gradually. But, over time, the situation will get >> worse, ultimately requiring the sensor to be replaced to restore >> peak engine performance. >> ... >> >> Don't Wait For Failure >> Replace Your Oxygen Sensor as Normal Preventive Maintenance >> >> To minimize the consequences of normal aging, Bosch recommends >> oxygen sensor replacement for preventive maintenance at the >> following intervals: >> Type of Car >> >> Mileage Replacement Interval Recommended >> Unheated oxygen sensors on 1976 to early 1990s vehicles >> Every 30,000 - 50,000 miles >> >> Heated (1st generation) oxygen sensors on mid-1980s to mid-1990s >> vehicles >> Every 60,000 miles >> >> Heated (2nd generation) oxygen sensors on mid-1990s and newer >> vehicles Every 100,000 miles >> _________ >> >> I'm not sure what the 93 7AFE has, does anyone know? >> >> I can just look under the hood... >> >> when the weather warms a little, it's -1 here in west Denver right >> now. >> > > First generation heated O2 sensor This is odd. I checked with Toyota and they said my car needs a Toyota 89465-19535 part. I cant find if that's heated or not, but Bosch recommends a 12201 which Autozone says is 2 wire unheated. Can anyone tell me please, if the Toyota part is heated or unheated?
From: Ray O on 20 Dec 2008 03:13 "Sarah Houston" <SHoust(a)pndfnospam.com> wrote in message news:Xns9B79ED5A464F2SntzldfrdSntzldfrdco(a)216.196.97.142... > "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : > >> <snipped> >>> I'm not sure what the 93 7AFE has, does anyone know? >>> >>> I can just look under the hood... >>> >>> when the weather warms a little, it's -1 here in west Denver right >>> now. >>> >> >> First generation heated O2 sensor > > This is odd. I checked with Toyota and they said my car needs a Toyota > 89465-19535 part. I cant find if that's heated or not, but Bosch > recommends a 12201 which Autozone says is 2 wire unheated. > > Can anyone tell me please, if the Toyota part is heated or unheated? > It doesn't matter whether or not the sensor is heated if you are looking up replacement parts, but on Toyotas, 2 wire sensors are heated, which is why I mentioned above that your car has a first generation heated O2 sensor. On a single wire sensor, the signal travels from the sensor to the computer. On a 2 wire sensor, the sensor signal travels down one of the wires to the computer, and the heater voltage travels from the computer down to the sensor. Even without a factory repair manual or wiring diagram, it is easy to check whether or not an O2 sensor is heated. When the With the engine cold, unplug the O2 sensor. Start the engine and measure voltage between each of the pins on the harness side of the connector and ground. If there is voltage between any of the pins and ground, the sensor is heated because the engine computer is sending power down the wire for the sensor heater. -- Ray O (correct punctuation to reply)
From: Sarah Houston on 20 Dec 2008 03:54 "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : > > "Sarah Houston" <SHoust(a)pndfnospam.com> wrote in message > news:Xns9B79ED5A464F2SntzldfrdSntzldfrdco(a)216.196.97.142... >> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : >> >>> ><snipped> >>>> I'm not sure what the 93 7AFE has, does anyone know? >>>> >>>> I can just look under the hood... >>>> >>>> when the weather warms a little, it's -1 here in west Denver right >>>> now. >>>> >>> >>> First generation heated O2 sensor >> >> This is odd. I checked with Toyota and they said my car needs a >> Toyota 89465-19535 part. I cant find if that's heated or not, but >> Bosch recommends a 12201 which Autozone says is 2 wire unheated. >> >> Can anyone tell me please, if the Toyota part is heated or unheated? >> > > It doesn't matter whether or not the sensor is heated if you are > looking up replacement parts, but on Toyotas, 2 wire sensors are > heated, which is why I mentioned above that your car has a first > generation heated O2 sensor. On a single wire sensor, the signal > travels from the sensor to the computer. On a 2 wire sensor, the > sensor signal travels down one of the wires to the computer, and the > heater voltage travels from the computer down to the sensor. Um, ok, I'm just baffled as to why they would ever need to heat an O2 sensor anyway. The thing has 600+ degree gases going by it? > Even without a factory repair manual or wiring diagram, it is easy to > check whether or not an O2 sensor is heated. When the With the > engine cold, unplug the O2 sensor. Start the engine and measure > voltage between each of the pins on the harness side of the connector > and ground. If there is voltage between any of the pins and ground, > the sensor is heated because the engine computer is sending power > down the wire for the sensor heater. I don't care so much, as long as I get the right replacement part in there and it doesn't wind up blowing something expensive up. But you're saying that doesnt matter? Like if I put that Bosch 12201 in, it should work fine and be ok?
From: Eternal Searcher on 20 Dec 2008 08:23 Sarah Houston wrote: > But you're saying that doesnt matter? Like if I put that Bosch 12201 in, > it should work fine and be ok? The likelihood of the Bosch working in your car is very low, so avoid it. Stick with OEM.
From: Ray O on 20 Dec 2008 17:21
"Sarah Houston" <SHoust(a)pndfnospam.com> wrote in message news:Xns9B7A13717AD9CSntzldfrdSntzldfrdco(a)216.196.97.142... > "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : > >> >> "Sarah Houston" <SHoust(a)pndfnospam.com> wrote in message >> news:Xns9B79ED5A464F2SntzldfrdSntzldfrdco(a)216.196.97.142... >>> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote : >>> >>>> >><snipped> >>>>> I'm not sure what the 93 7AFE has, does anyone know? >>>>> >>>>> I can just look under the hood... >>>>> >>>>> when the weather warms a little, it's -1 here in west Denver right >>>>> now. >>>>> >>>> >>>> First generation heated O2 sensor >>> >>> This is odd. I checked with Toyota and they said my car needs a >>> Toyota 89465-19535 part. I cant find if that's heated or not, but >>> Bosch recommends a 12201 which Autozone says is 2 wire unheated. >>> >>> Can anyone tell me please, if the Toyota part is heated or unheated? >>> >> >> It doesn't matter whether or not the sensor is heated if you are >> looking up replacement parts, but on Toyotas, 2 wire sensors are >> heated, which is why I mentioned above that your car has a first >> generation heated O2 sensor. On a single wire sensor, the signal >> travels from the sensor to the computer. On a 2 wire sensor, the >> sensor signal travels down one of the wires to the computer, and the >> heater voltage travels from the computer down to the sensor. > > Um, ok, I'm just baffled as to why they would ever need to heat an O2 > sensor anyway. The thing has 600+ degree gases going by it? > The sensor has to be operating temperature to work properly and is one of the parameters that has to be met for the engine computer control to go into closed loop operation. When the system is in closed loop mode, the sensor detects the amount of oxygen, or O2 in the exhaust gas and varies the voltage it puts out. The computer monitors the output voltage and adjusts the amount of fuel injected to try to maintain the optimal ratio of air to fuel. When the sensor is cold, it doesn't put out the proper voltage so almost all newer sensors are heated so they reach operating temperature more quickly and allow the system to go into closed loop operation. The system will be in open loop mode under certain conditions, like cold coolant, cold O2 sensors, or when the throttle is open past a certain point. When the system is in open loop mode, the computer uses pre-determined default values to determine how much fuel to inject. While the engine will run fine in open loop mode, it is a little dirtier and uses a little more fuel. >> Even without a factory repair manual or wiring diagram, it is easy to >> check whether or not an O2 sensor is heated. When the With the >> engine cold, unplug the O2 sensor. Start the engine and measure >> voltage between each of the pins on the harness side of the connector >> and ground. If there is voltage between any of the pins and ground, >> the sensor is heated because the engine computer is sending power >> down the wire for the sensor heater. > > I don't care so much, as long as I get the right replacement part in > there and it doesn't wind up blowing something expensive up. > > But you're saying that doesnt matter? Like if I put that Bosch 12201 in, > it should work fine and be ok? > It doesn't matter as long as you have the correct replacement part number. I do not have any personal experience with Bosch O2 sensors, but I have seen problems with aftermarket ignition and emissions parts in Toyotas, so I usually prefer OEM. Bosh O2 sensors are probably OK, but their recommendation for a relatively short replacement interval would bother me, and I would be surprised if you get a noticeable improvement in fuel economy -- Ray O (correct punctuation to reply) |