NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #16  
Old February 1st, 2010, 21:21
xjbubba xjbubba is offline
NAXJA Member # 1524
 
Join Date: Jan 2004
Location: santa barbara, ca
Posts: 1,270
Re: Testing Jeep O2, Oxygen sensors

Not much experience with the Renix O2 sensor. I had a problem with my 4.0, but it was an open O2 heater circuit, found using an ohm meter.
The digital VOM works fine for testing the HO O2 sensors (they're the same as GM units). The last high impedance analog volt meter I had access to, besides an o-scope, was a vacuum tube VOM. I find it hard to beat the accuracy of the digital meter, especially when you take into consideration parallax and meter movement error.
Reply With Quote
  #17  
Old February 3rd, 2010, 01:43
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by xjbubba View Post
Following the guidance gleaned from the "web", I've benched tested O2's, with good results.
The test is simple: Place the sensor in a vise gingerly, and connect the meter's ground lead to the vise jaw, next to the sensor (I try to capture the bare test lead between the vise body and the sensor outer shell). Connect the plus probe to the sensor's output lead.
Using a propane torch, heat the tip of the sensor. It won't take long for a good sensor to show 900mv. Remove the heat, and the reading should drop to near zero almost instantly.
You can check them on the vehicle by connecting the sensor output lead to the meter's positive lead (I like to leave the sensor in the circuit, and back-probe the output lead), and the meter's ground lead to the engine block (1 or 3-wire sensors). With engine off, but the ignition on, you should read .450v. This indicates a good circuit to the ECM. With the engine running, and warmed up, the meter should be bouncing between 100 and 800mv; this indicates the O2 sensor is warm and properly active. To test the ability for the sensor and the ECM to work in closed loop, first pull a large vacuum line, such as the brake booster hose loose, and observe the O2 output. There should be a rapid decrease in the voltage, indicating the mixture has gone lean. The ECM should try to compensate by enriching the mixture, driving the O2 output back to normal. Replace the vacuum hose, and after the engine normalizes, introduce propane into the throttle body (not lit--and wear safety goggles). This should cause the O2 signal to move rapidly higher, indicating a rich mixture.
Results from the above tests will tell you if your O2 sensor is functional; however, it will not completely rule out a slow, or "lazy" sensor. An o-scope is needed for that, but bench test described above, using a lit propane torch can give a decent indication of laziness, if the sensor's out put doesn't instantly drop off when the flame is removed, or rapidly increase when the flame is re-applied after once being brought to operating temp.
The Renix O2 sensor can not be tested that way off the vehicle. It needs to be tested while in use, as I have said before. It is a variable resistor, not a 0-1 volt output device.

I do not believe this statement is correct: "With engine off, but the ignition on, you should read .450v. ", It should read an extreme reading IIRC, like near 0 volts (IIRC, and your test results you state above suggest it is 0 volts), until it is hot, over 600 F IIRC, and then with the engine off, sensor hot (ignition in run, but engine off, O2 sensor hot after say 30 seconds due to O2 sensor internal heater warm up, but I do not know if OBD-I or OBD-II pre-heats the sensor with the engine off?), it should read extremely lean (I forget if that .1 or .9 volts on the newer 91 model and newer O2 sensors in Jeeps) it should not read .450 with no combustion, but rather extremely lean.

You don't need to pull the O2 sensor to test it. You also don't need to use propane. Simply press the throttle to move it to a lean reading for a few seconds, and then let off the throttle to force it rich, and watch the analog volt meter (high impedance meter) needle response. Also running the rpm up to 2000 rpm tests the O2 sensors response speed. At 2000 rpm the The voltage should hold very tight in a .40 to .50 range or tighter. At idle it should bounce from about .02 to .07 about once per second. If it is slow to bounce, like several seconds, say 4-5 or more seconds there is a problem. But the problem could be something like a cracked exhaust manifold, or engine valve problem, so at that point a bench test for the newer (91-01) sensors might make sense to verify the source of the problem (sensor sensitivity, engine, manifold, wiring, or computer).

Here is the meter I have been using for 35 years now (ebay link below). It is a Micronta 22-210 Analog FET Multimeter. Radio shake was still selling something like this not too long ago, but I don't see on their web site today, just the parts manual...

http://cgi.ebay.com/Micronta-22-210-...item3ca9b2c0b7


This might be an interesting option I would consider, it is a digital (20 meg ohm internal impedance) with an analog bar meter. never tried it, or one like it before, but it would give an analog bar signal for the switching frequency to be displayed. And not terribly expensive. It also shows a frequency test range that looks like it might be useful for testing the CPS as well as O2 and maybe even the TPS noise tests? But I am speculating on that.


http://cgi.ebay.com/VC99-3-6-7-Multi...item5885e27956

After some long searching, I finally found one here that meets the analog high impedance requirements, but I have not found a US source or price. It does not look expensive, and made in India.

I found a number of analog meters, cheap ones, that ranged fron 600 ohms per volt up to 40,000 ohms per volt input impedance, but I do not know if the 20,000 or 40,000 ohm per volt models are high enough for Renix or HO year O2 sensors. Be nice if one of the EE's around could post us a calc on the loss in accuracy we might see for either O2 sensor test, but they may need more data than we have on the sensors max output current (HO) and Renix max signal current, and Renix O2 sensor resistance range (span). I suspect the Renix can handle a 20,000 ohm per volt meter, with out much error (but not sure), as I think (IIRC) the Renix O2 sensor runs around 20,000 ohms at stoich. I do know it drops the 5 volt ECU input voltage to 2.45 volts at stoich, and at 4.5 volts the O2 sensor resistance is real high, and at 1 volt it is a lot lower tha 40,000 ohms. I think the Renix O2 sensor resistance is in an old thread here, from when I found it a few years ago (maybe an old MPG thread about biasing the Renix O2 sensor with a variable resistor in series or parralell) One of these days I may try both analog meters that I have to see how much difference a 20,000 ohm/ volt input impedance meter will throw off the true reading. The one I have and normally use is 10 meg ohm.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091

Last edited by Ecomike; February 3rd, 2010 at 02:14.
Reply With Quote
  #18  
Old February 3rd, 2010, 02:20
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by xjbubba View Post
Not much experience with the Renix O2 sensor. I had a problem with my 4.0, but it was an open O2 heater circuit, found using an ohm meter.
The digital VOM works fine for testing the HO O2 sensors (they're the same as GM units). The last high impedance analog volt meter I had access to, besides an o-scope, was a vacuum tube VOM. I find it hard to beat the accuracy of the digital meter, especially when you take into consideration parallax and meter movement error.

I still have my dad's old WWII stuff, WWII army air corp surplus ham radio stuff, tube tester, tube style o-scope, tube style VOM, all gathering dust. But they make much better dust catchers than my ex's old junk did.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #19  
Old February 3rd, 2010, 02:26
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by OkieXJ View Post
http://www.allspectrum.com/store/pro...FZMK5Qod1BBPtg

I think I might try and find something like this to test my O2 sensor and make sure its fluctuating properly. Its input impedence is 1Mohm. I need to do something cause I'm getting around 11.5 MPG. I fear the cause might be poor compression due to worn piston rings though.
Is it using a lot of oil? You might try disconnecting the O2 sensor to see if mileage drops further. A bad O2 sensor seems to waist about 6 mpgs of gas on our rigs. If the mileage is unchanged in a tank of gas with no O2 sensor connected, then your MPG problem is at least partly an O2 sensor problem. But you need to find out if it is the sensor, bad wiring (all too common, they tend to get intimate with exhaust pipes, the wires), or a bad ECU, or cracked Ex-manifold.....before buying a new sensor.


Interesting rig you found there. Certainly priced right. I wonder if it would test the CPS too?
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #20  
Old February 3rd, 2010, 02:35
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by 5-90 View Post
I'm happy to see a thread like this - I haven't devised a test for the sensing element yet (and considering that you need to get the thing up around 700*C to get valid sensor readings, this isn't exactly something you can do easily "on the bench...) so I'll be interested in seeing what comes of this!
If you read the first 2 posts in the thread, I posted how to do live tests on Both HO and Renix, with the engine runnning. No need to reinvent the wheel. I got the Renix live on board test method from and old timer at Bosch, that knew the Renix O2 sensor all too well. Only issue which xjbubba brought up was the meter choice we are now debating. Renix only takes a few seconds (30 seconds max here, but those tests were at 60 F ambient or higher) to switch to closed loop from a cold start if everything else is working.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #21  
Old February 3rd, 2010, 02:39
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by xjbubba View Post
Not much experience with the Renix O2 sensor. I had a problem with my 4.0, but it was an open O2 heater circuit, found using an ohm meter.
The digital VOM works fine for testing the HO O2 sensors (they're the same as GM units). The last high impedance analog volt meter I had access to, besides an o-scope, was a vacuum tube VOM. I find it hard to beat the accuracy of the digital meter, especially when you take into consideration parallax and meter movement error.

My analog has 2 zero knobs, one for volts, another for ohms, that you use to calibrate the meter before each test (compensates for battery age), and it has a silver mirror behind the neddle for eliminating the parallax error. But you are right concerning cheaper design analog meters. I have found digitals to be error prone just before the battery dies, just like analogs.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #22  
Old February 3rd, 2010, 02:43
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by 5-90 View Post

Have you run across a similar testing procedure for HEGO units akin to our RENIX ones?
See my first 2 posts, first one for Renix, the other for HOs. I got tired of posting it weekly here in a thousand threads, so I gave it a thread with an easy to find title and you still missed it!

LOL.

xjbubba,

I might add that the bench test you described could be run by hot wiring the O2 heater wires to a 12 volt car battery (make damn sure you know which wires folks, or you might fry the O2 sensor), then all you need is to vary the O2 concentration locally, using say propane, or nitrogen gas. Nitrogen, if available would be safer. CO2 gas should work too.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091

Last edited by Ecomike; February 3rd, 2010 at 02:50.
Reply With Quote
  #23  
Old February 3rd, 2010, 05:02
techno1154's Avatar
techno1154 techno1154 is offline
NAXJA Member
 
Join Date: Apr 2003
Location: In the islands
Posts: 2,233
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by Ecomike View Post
Is it using a lot of oil? You might try disconnecting the O2 sensor to see if mileage drops further. A bad O2 sensor seems to waist about 6 mpgs of gas on our rigs. If the mileage is unchanged in a tank of gas with no O2 sensor connected, then your MPG problem is at least partly an O2 sensor problem. But you need to find out if it is the sensor, bad wiring (all too common, they tend to get intimate with exhaust pipes, the wires), or a bad ECU, or cracked Ex-manifold.....before buying a new sensor.


Interesting rig you found there. Certainly priced right. I wonder if it would test the CPS too?
On my XJ, if the primary O2 sensor is disconnected the engine will not run past the initial 5 minutes after a cold startup. It must be connected and be working reasonably well. Also a bad O2 sensor causes the engine to stumble at highway speed and shut down on the city streets. It will restart after about 15 minutes and run for another 5 minutes. The sensor in the cat triggers the check engine light but that is all.
__________________
Patrick

#594
1996 XJ; 4.0L; AW4; NP231; SYE; D30 and D44; ECTED; 4.10 gears; 30X9.5 -15 BFG/AT/KO; 3" lift; Rusty's LCA; JKS ADJ UCA; Kevins ADJ Track bar; Drawtite Front Receiver; Dual Electric Fans; Dual Battaries.
Reply With Quote
  #24  
Old February 3rd, 2010, 09:32
xjbubba xjbubba is offline
NAXJA Member # 1524
 
Join Date: Jan 2004
Location: santa barbara, ca
Posts: 1,270
Re: Testing Jeep O2, Oxygen sensors

In response to Ecomike's comment stating my testing procedure is in error regarding the output of an O2 sensor with the key on/engine off, I'll stand by my "guidance". Now, first, I stated in another post that I had minimal experience with Renix O2 sensors, but was referring to Jeep HO and similar O2 sensors (like the ones GM has been using since the mid '80s); I've had extensive experience testing the more common sensors. When you back probe the sensor output lead, and turn the key to "ign", you are looking at the ECM generated reference voltage--not the O2's output. Obviously, with engine not running, there will be no output.
If you read "0" volts in this circumstance, as Ecomike suggests you should, that would indicate a problem with either the wire, or with the ECM. That's why it's a good first step in testing the ECM circuit.
And, no, it's not necessary (or recommended by me) to pull the O2 sensor out of the exhaust to test it; however, if you have a couple of sensors laying about, for whatever reason, it's easier to "bench" test them than to install them in the exhaust just for that purpose.
I don't care what kind of meter you want to use for testing electronic circuitry, it should be high impedance. For testing low-end devices, like resistors, capacitors, transformers, most any analog multimeter will work, and for some cases, as previously discussed (the TPS for example), the analog meter is preferred. That said, the analog meter requires more interpretive skills than a digital meter to use correctly and accurately; also the meter is most accurate in the upper 1/3rd of the select range. There are no issues with parallax or meter movement error to consider with the digital multi-meter. The problem with the digital meter is that it uses circuits to convert from analog to digital, requiring it to sample detected voltage at some predetermined rate (such as to times per second). I might add that anytime you're using a scanner to look at engine sensor data, the operation is the same as using a digital meter; the ECM is converting the sensor data to digital and sampling the converted data at some predetermined rate. This sampling requirement reduces the digital meters effectiveness in testing varying DC voltage, or varying resistive values, such as seen when testing a TPS for discontinuity (bad spots); a relevant reading may be lost between samples.
As far as high or low impedance goes, most people in the business would call 40k ohm/volt low impedance. Testing an O2 on the 3-volt range would be the same as putting 120k resistor in parallel with the sensor--not good. The digital meter (the common variety most of us have) is like placing a 10 meg-ohm resistor in parallel. With the circuits we test (automobile ECM/PCMs), 10 meg-ohms will not affect the readings in a material way.
The best I can tell searching for info on the E-bay meter you sited as using over the last 35 years, the Micronta 22-210, the unit is a 30k ohm/volt multimeter--not good, in my opinion, for testing active electronic circuits or components: "22-210 30,000 OHMS/VOLT MULTITESTER".
With regard to using nitrogen or CO2, neither will accomplish the objective of richening the mixture to test O2 response. Since the test I described required the engine to be running, the O2 heater circuit should also be active, by default.
Reply With Quote
  #25  
Old February 3rd, 2010, 10:16
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Quote:
Originally Posted by xjbubba View Post
In response to Ecomike's comment stating my testing procedure is in error regarding the output of an O2 sensor with the key on/engine off, I'll stand by my "guidance". Now, first, I stated in another post that I had minimal experience with Renix O2 sensors, but was referring to Jeep HO and similar O2 sensors (like the ones GM has been using since the mid '80s); I've had extensive experience testing the more common sensors. When you back probe the sensor output lead, and turn the key to "ign", you are looking at the ECM generated reference voltage--not the O2's output. Obviously, with engine not running, there will be no output.
If you read "0" volts in this circumstance, as Ecomike suggests you should, that would indicate a problem with either the wire, or with the ECM. That's why it's a good first step in testing the ECM circuit.
And, no, it's not necessary (or recommended by me) to pull the O2 sensor out of the exhaust to test it; however, if you have a couple of sensors laying about, for whatever reason, it's easier to "bench" test them than to install them in the exhaust just for that purpose.
I don't care what kind of meter you want to use for testing electronic circuitry, it should be high impedance. For testing low-end devices, like resistors, capacitors, transformers, most any analog multimeter will work, and for some cases, as previously discussed (the TPS for example), the analog meter is preferred. That said, the analog meter requires more interpretive skills than a digital meter to use correctly and accurately; also the meter is most accurate in the upper 1/3rd of the select range. There are no issues with parallax or meter movement error to consider with the digital multi-meter. The problem with the digital meter is that it uses circuits to convert from analog to digital, requiring it to sample detected voltage at some predetermined rate (such as to times per second). I might add that anytime you're using a scanner to look at engine sensor data, the operation is the same as using a digital meter; the ECM is converting the sensor data to digital and sampling the converted data at some predetermined rate. This sampling requirement reduces the digital meters effectiveness in testing varying DC voltage, or varying resistive values, such as seen when testing a TPS for discontinuity (bad spots); a relevant reading may be lost between samples.
As far as high or low impedance goes, most people in the business would call 40k ohm/volt low impedance. Testing an O2 on the 3-volt range would be the same as putting 120k resistor in parallel with the sensor--not good. The digital meter (the common variety most of us have) is like placing a 10 meg-ohm resistor in parallel. With the circuits we test (automobile ECM/PCMs), 10 meg-ohms will not affect the readings in a material way.
The best I can tell searching for info on the E-bay meter you sited as using over the last 35 years, the Micronta 22-210, the unit is a 30k ohm/volt multimeter--not good, in my opinion, for testing active electronic circuits or components: "22-210 30,000 OHMS/VOLT MULTITESTER".
With regard to using nitrogen or CO2, neither will accomplish the objective of richening the mixture to test O2 response. Since the test I described required the engine to be running, the O2 heater circuit should also be active, by default.
Two comments or questions, one, do you have a link to the .45V reference voltage on the ECM (PCM) reference voltage to the O2 sensor on the HO models with power on, run mode, but engine off? Or is this just your own test data. Either way is it the same for OBD-I and OBD-II years? I find it a little strange they would supply a test volatge in the that mode, but pehaps they had pre test reasons.

Second, the CO2 / nitrogen comment was for bench testing, not live in the running engine testing. Sorry if I was clear on that.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #26  
Old February 3rd, 2010, 11:57
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

FSM says the Renix O2 sensor operating temperature is "1475 F (850 C)".
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #27  
Old February 3rd, 2010, 22:12
xjbubba xjbubba is offline
NAXJA Member # 1524
 
Join Date: Jan 2004
Location: santa barbara, ca
Posts: 1,270
Re: Testing Jeep O2, Oxygen sensors

I don't have specific sites for the Jeep HO engine PCM, but do have sites for the use of the .450v for fuel injection control systems using the zirconia oxygen sensor. This is the sensor type used to control air/fuel mixture in the 90 up Jeep, and many other vehicles.
Besides the sites I pasted below, I quote page 3-10 from my 1994 C/K (GM) truck driveability, emissions and electrical diagnosis manual: "--The control module puts out a reference signal of 0.45 volt (450mV). The reference signal serves two purposes. The first is to run the engine when it is in "open loop" mode of operation.---" It then goes on to explain "closed loop" operation, and the use of the reference signal to control the air/fuel mixture.
I know this info is valid for OBD-I Jeeps and GM trucks/cars, and I believe many OBD-II vehicles, who are using zirconia sensors, also follow similar practice with regard to the .450v reference signal.

Info relative to Renix O2 sensors:

http://www.dnd-automotive.com/tuneup/02-sensor.htm
Some vehicles are equipped with a different type of O2 sensor that has a titania rather than zirconia element. Instead of generating its own voltage signal, a titania O2 sensor changes resistance as the air/fuel ratio goes from rich to lean. Instead of a gradual change, it switches from low resistance (less than 1,000 ohms) when the mixture is rich, to high resistance (over 20,000 ohms) when the mixture is lean.
The engine computer supplies a base reference voltage of approximately one volt to the titania O2 sensor, and then reads the voltage flowing through the sensor to monitor the air/fuel ratio.
When the fuel mixture is rich, resistance in a titania sensor will be low so the voltage signal will be high (close to 1.0 volt). When the fuel mixture is lean, resistance increases and the voltage signal drops down to about 0.1 volt.
Compared to the more common zirconia O2 sensors, titania sensors have three advantages: (1) they don't need an air reference (there is no internal venting to the outside atmosphere to plug up); (2) they have a fast warm-up time (about 15 seconds); and (3) they work at lower exhaust temperatures (they won't cool off at idle and they can be located further downstream from the engine or used with turbochargers).
Chrysler also uses them on the Jeep Cherokee and Wrangler (because of the sensor's ability to handle off-road driving through water), and the Eagle Summit.

Info relative to the standard zirconia (as in '90 up Cherokee) sensor

http://www.brakeandfrontend.com/Arti...xygen_Sen.aspx


Based on the oxygen sensor voltage, the controller will increase or decrease the pulse width of the injector, which in turn will change the oxygen sensor voltage for the next injector pulse. The oxygen sensor is also referred to as a lambda (l) 1 sensor. Lambda is the Greek letter equivalent to L. Lambda (l) 1 is the reference voltage of 450 mV. l 1 represents an air fuel ratio of 14.7:1 or stoichiometric. The controller will drive the injector pulse from rich to lean and lean to rich to maintain a stoichiometric air fuel ratio.

http://answers.yahoo.com/question/in...3215158AAa4lA8

The Powertrain control module
(PCM) will provide a .45 volt reference voltage to the Oxygen sensor. When the O2 sensor reaches operating temperature, it will generate a voltage that will vary depending on the oxygen content of the exhaust.

http://www.sjmautotechnik.com/troubl.../10vo2sen.html

If the O2 sensor wire is disconnected with the engine running, the ECU normally has a 0.450 V (+/- 0.050V) reference voltage on the ECU wire connecting to the O2 sensor.
Reply With Quote
  #28  
Old February 4th, 2010, 16:31
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

Unless I am mistake (and I don't think I am), the 90 model was a Renix, not OBD-I. Also Renix used a 5 volt not a 1 volt signal. So they have 2 errors in those links.

I don't get the reference voltage on OBD-I and II, It makes absolutely no sense to me at all why they would have the computer send a reference voltage to a voltage producing sensor while it is running. That just seems bizzare.

Have you actually seen .45 volts on the sensor "computer side" wire of a disconnected O2 sensor on 91-01 model while the engine was running? I understand you said earlier that you have seen it, with power on, engine off... or something to that effect. I don't have any non renix jeeps, and I have not played with son's 96 Ford Taurus O2s yet (but that happen soon) so IO have no way currently to verify it.

Thanks for your posts and contributions (I do appreciate your input!), but for others reading this thread, let me say that I started it because of the number of wrong and incomplete posts on other sites that had incomplete information on our O2 sensors or info that was simply wrong. So don't take my arguments the wrong way, I just have seen so much wrong stuff, I don't take anything at face value anymore.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #29  
Old February 4th, 2010, 16:50
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

The guy answering on the yahoo site:

http://answers.yahoo.com/question/in...3215158AAa4lA8

Contradicts himself, he goes from a .45 V reference voltage statement early on to a 5 volt signal from the PCM to the O2 sensor later in his same disertation. Not sure what to make of that. He is answering a question about a 2000 infiniti g2.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #30  
Old February 4th, 2010, 17:09
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: MilkyWay Galaxy
Posts: 15,064
Re: Testing Jeep O2, Oxygen sensors

The other site is talking about a "ECU System,
1986-90 5000/200TQ", Audi.

Not about jeeps.

http://www.sjmautotechnik.com/troubl.../10vo2sen.html
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Oxygen sensors JCwarrior88 OEM Tech Discussion 15 March 13th, 2011 03:51
oxygen sensors and or a pcm reflash?..... moparjim1987 OEM Tech Discussion 39 June 27th, 2008 07:33
Oxygen Sensors casm OEM Tech Discussion 10 September 12th, 2005 14:17
oxygen sensors CITYBOY OEM Tech Discussion 8 November 25th, 2004 05:43
Oxygen Sensors Nick OEM Tech Discussion 7 July 7th, 2004 21:17


All times are GMT -7. The time now is 21:34.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014