question on O2 sensors for you motor heads

I thought Mazda trucks had downloadable fault checking systems, IE you take the truck to a garage and he plugs your truck into a machine that downs the operating system and fault library, if you could get this done not only wouldit tell you what is out of spec but also the record of why the wearning light comes on, re O2 sensors IIRC they either work or they dont so if they are working now perhaps leaving well alone is the best bet???

"The Rifleman" wrote in news:c5g89d$n00$ snipped-for-privacy@news7.svr.pol.co.uk:

You can pull a rough list of codes with the key-on-off method and counting the pulses of the light. These may not be very specific codes, but will get you in the general direction. Around here (E. Tenn), dealers charge $40-50 to run a scan on the vehicle and give you the results. While this may seem high, it certianly is better than replacing $300 worth of parts in an attempt to fix a problem.

By the light coming on at coast/decel, it could be valve guide seals (sucking oil into the combustion chamber), worn rings (sucking oil into the combustion chamber), loss of vacuume (bad hose/seal), or any number of other causes (changed the air filter and vent filters lately?)

Gunner wrote in news: snipped-for-privacy@4ax.com:

If its the O2 sensors in the exhaust manifold , its probably better idea to use parts that suit your car, not the truck the new motor came out of since the engine management in your car will be looking for them bits , not truck bits.

fwiw myal

Good news/bad news:

Bad news - those sensors are *shot*, and replacing a "one-wire" with anything else but a one-wire is useless.

Good news - the only thing hurt is gas mileage, and "generic" one-wires can be had for about $25 per - I'll dig for a website after work today...

CC

I'm in E TN and my local mechanic (NOT dealer) checks the codes for free. He figures if he finds something wrong he will get the business. He's right; he found a bad temp sensor and got the job replacing it (cost less than $40).

NO NO NO !!!!!!! DO NOT INSTALL !!!!!

It will have a differrent resistance (the resistance changes depending on the amount of O2 (the computer measures the resistance and adjusts the air/fuel mixture from that reading) Also the exhust on your truck has a higher temp than a car, many different factors here, installing the wrong O2 sensor will end up costing you a moter.

Take the damn thing in a have it scanned, you may have an EGR valve going bad, an O2 sensor can also cause the engine to run rich if its reading wrong.

Is this moter carberated ? If so have the idle mixture controll silinoid checked, also check the coasting valve. Fuel infected (injected) ? Check for vacume leaks, check the fuel presure regulator, PUT THE DAMN THING ON THE SCANNER !!!

But what ever you do, Do not R&R with a part from another car, just asking for trouble, this is not the old days :-)

Spring the hundred bucks AND GET THE CORRECT PART !!! The computer uses to O2 sensor to tell it where to set the air fuel ratio.

campaign contributions,

secrets to the Chinese,

cares less,

high-level government pizza."

Bad valve guides WILL NOT make the "Check Engine Light" come on, only a sensor will do that.

I have heard that Action Auto (parts store chain) will test for free. I did some poking around and found this also:

"Electronic Engine Control self test for Ford vehicles with EEC IV"

Not sure how helpful it is.

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Gunner,

You can find inexpensive code readers at most auto parts stores these days. I paid about $20 for mine.

Peter

campaign contributions,

secrets to the Chinese,

little and cares less,

pairs for the U.N.,

delivering high-level government pizza."

I'd get the proper sensor. If it only has a single wire coming from it, it's probably the cheapest possible type, you can likely pick one up for about $25. Check Ebay. You'll save that much in fuel pretty quick. If you wish to persist with the junkyard ones, the extra wires are for a heater and temp sensor. Good luck figuring out which wire does what.;-)

Pete

->- __ Pete Snell Royal Military College Kingston Ontario snipped-for-privacy@rmc.ca

The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. - George Bernard Shaw

They are 4 wire.

Gunner

Some may decry the impeachment of William Jefferson Clinton as a national trauma, but not humorist P.J. O'Rourke, who thinks the proceedings are a win-win situation

-- and grand entertainment to boot. Mr. O'Rourke, writing in the latest issue of the Weekly Standard, acknowledges that "some earnest souls have gone so far as to aver that impeachment has distracted President Clinton from ... raising taxes, destroying health care, appointing 1960s bakeheads to high political office, soliciting felonious campaign contributions, hanging friends out to dry for Arkansas real estate frauds, giving missile secrets to the Chinese, taking credit for the benefits of a free market about which he knows little and cares less, using U.S. military forces as fig leaves for domestic scandals and au pairs for the U.N., leading foreign policy back into the flea circus of Jimmy Carterism, having phone sex, groping patronage seekers, and snapping the elastic on the underpants of psychologically disturbed school-age White House interns entrusted with the task of delivering high-level government pizza." Ouch. Tell us what you really think, P.J. "No matter what, Bill," Mr.O'Rourke concludes, "your girlfriend's ugly, your wife hates you, and your dog can't hunt."

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I did the blinking light thingy a couple weeks ago. No codes showed other than the normal. I understand the verbose historical code hardware was installed in the later models. The codes on most of the O2 stuff on this truck only read when the light is on, and Ive been unable to get the light to come on, except at speed under certain circumstances.

Gunner

Some may decry the impeachment of William Jefferson Clinton as a national trauma, but not humorist P.J. O'Rourke, who thinks the proceedings are a win-win situation

-- and grand entertainment to boot. Mr. O'Rourke, writing in the latest issue of the Weekly Standard, acknowledges that "some earnest souls have gone so far as to aver that impeachment has distracted President Clinton from ... raising taxes, destroying health care, appointing 1960s bakeheads to high political office, soliciting felonious campaign contributions, hanging friends out to dry for Arkansas real estate frauds, giving missile secrets to the Chinese, taking credit for the benefits of a free market about which he knows little and cares less, using U.S. military forces as fig leaves for domestic scandals and au pairs for the U.N., leading foreign policy back into the flea circus of Jimmy Carterism, having phone sex, groping patronage seekers, and snapping the elastic on the underpants of psychologically disturbed school-age White House interns entrusted with the task of delivering high-level government pizza." Ouch. Tell us what you really think, P.J. "No matter what, Bill," Mr.O'Rourke concludes, "your girlfriend's ugly, your wife hates you, and your dog can't hunt."

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How about checking the voltage output of the old sensors with a DVOM or preferably, an oscilloscope?

Transition time from low voltage to high and vice versa should be less than 200 milliseconds. Force the fuel system lean by creating a vacuum leak, the voltage should go below 200 millivolts, force the fuel system rich by bleeding in some raw propane or carb cleaner , the voltage should go above 800 millivolts.

As for the check engine light, best would be to extract the trouble codes and see where they lead you, but knowing the system and it's trouble spots, I'd take a SWAG at the Mass Airflow Sensor element being a little dirty. The MAF sensor is mounted on the air cleaner, at its outlet to the engine it's working element (the part where the harness plugs in) is held to the sensor body by three anti-tamper Torx(TM) screws. Remove the sensor element and clean the filament with a cotton swab and some electronic or tuner cleaner (be gentle).

If an O2 sensor is bad then the "Check Engine" light should come on. If the light stays off then either the bulb is burnt out or else you should leave the oxygen sensors alone. I sure as hell wouldn't replace probably-good O2 sensors with probably-the-wrong-part O2 sensors.

The people over in the newsgroup rec.autos.makers.mazda might have more to say on this subject.

Why a different exhaust temp? Same engine (albit sideways in the car), same smog stuff, same fuel injectors etc. In fact, the engine thats in there now came out of a car. The long block simply needed the original water pump housing installed and the original injector manifold and fuel rail, and set in the truck front to back.

Gunner

Some may decry the impeachment of William Jefferson Clinton as a national trauma, but not humorist P.J. O'Rourke, who thinks the proceedings are a win-win situation

-- and grand entertainment to boot. Mr. O'Rourke, writing in the latest issue of the Weekly Standard, acknowledges that "some earnest souls have gone so far as to aver that impeachment has distracted President Clinton from ... raising taxes, destroying health care, appointing 1960s bakeheads to high political office, soliciting felonious campaign contributions, hanging friends out to dry for Arkansas real estate frauds, giving missile secrets to the Chinese, taking credit for the benefits of a free market about which he knows little and cares less, using U.S. military forces as fig leaves for domestic scandals and au pairs for the U.N., leading foreign policy back into the flea circus of Jimmy Carterism, having phone sex, groping patronage seekers, and snapping the elastic on the underpants of psychologically disturbed school-age White House interns entrusted with the task of delivering high-level government pizza." Ouch. Tell us what you really think, P.J. "No matter what, Bill," Mr.O'Rourke concludes, "your girlfriend's ugly, your wife hates you, and your dog can't hunt."

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Gunner,

My blinky light thingy (for a '93 Cobra motor) will read the historical codes. There's a second round of blinky lights that one must read. It's a different motor but still a "Ford" and earlier than your car...

Peter

PS FWIW (which is obviously absolutely nothing), I had a Civic that would illuminate the check engine light ONLY when coming out of the west bound Caldecott tunnel in the Bay Area. About one time out of five, a half mile west of the tunnel the FI light would go on. It NEVER happened anywhere else and I owned that car for 125K miles. Some weird signal was permeating the airwaves at that spot that caused something wonky to happen with my ECU. Maybe you have ghosts in your car?

campaign contributions,

secrets to the Chinese,

little and cares less,

pairs for the U.N.,

delivering high-level government pizza."

||>

||>Good news - the only thing hurt is gas mileage, and "generic" one-wires can ||>be had for about $25 per - I'll dig for a website after work today... ||>

||>

||>CC ||>

||They are 4 wire.

You can get a 13913 Bosch from AZ for $37. It's a 4-wire universal, cut and crimp. Rex in Fort Worth

I am no expert on O2 sensors, but have looked around on the web and my impression is that all the O2 sensors generate a voltage that sensed by the computer. The computer either senses it as above of below a value. It does not sense an actual value. Some O2 sensors have a heater incorporated in them so they heat up quicker. They don't work until they are at about 600 degrees F as I remember ( screws up using them on my wood stove ). I think you can use a digital multimeter to sense the voltage while driving the car/truck, and it should fluctuate above and below the threshhold voltage ( 1.6 volts as I remember ). Do a little googling and see if you can't find similar information on how to check the O2 sensor that is now in the truck. Oh yes don't use a low impedance voltmeter to check the sensor. The sensors don't put out a low impedance signal and putting a low impedance meter on them may damage them.

So to sum up, I think all the O2 sensors work the same way and put out the same voltage. You can check your original sensor and if bad replace it with anything that screws in and connects. ie replace a sensor with heater with another one with a heater.

Again I am not an expert. Google for better info.

Dan

FWIW, the O2 sensors put out a voltage, not a change a resistance. The element needs to be hot to work and once above the minimal temp, the voltage out is related to the gasses going by the element. The number of wires depends upon whether there is a ground wire for the sensor and whether the heater element uses the exhaust pipe for a ground also. There is only one car maker that uses anything interestingly different and that was Honda for a few cars in the mid '90s when they used an extended range one which is nice for doing F/A mixture gauges as it will measure a much wider range of mixtures.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!