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-   -   O2 sensor: Location and testing (http://www.jeepgarage.org/f181/o2-sensor-location-and-testing-65028.html)

phottomatt 09-04-2013 08:16 AM

O2 sensor: Location and testing
 
I've been looking for a couple days now and just can't find it. Can someone please help me out? Is there a post or some info on how to check the O2 sensors, I think you can check the resistance on them. Also I think there are 4 all together one of which is difficult to get to.

Thanks.

crewstopher 09-04-2013 08:56 AM

Re: O2 sensor: Location and testing
 
I believe they are located on the exhaust pipes, 2 for each side, both pre and post cat. Look towards the top sides of the pipes. I think you can locate all of the sensors from beneath the vehicle. I cannot comment on testing the resistance, but I am curious.

phottomatt 09-04-2013 09:43 AM

Re: O2 sensor: Location and testing
 
That makes sense on the location, thanks. And I found a method for testing.
O2 sensor test

jeepgcoman 09-04-2013 01:46 PM

Re: O2 sensor: Location and testing
 
As you can see by the testing instructions, this won't be a picnic. Generally, testing the sensors is more trouble than it's worth. If you do any testing, the best way is to find some sort of millivolt monitoring device. I use my on board DashHawks on both my vehicles. Testing with a meter at the sensor would not be fun on a hot exhaust, with the engine running. If you have no good, easy way of testing them, and you suspect them to be your problem, IMO, just replace them. That's not so easy either. Total cost of the 4 sensors should be no more than ~$125. You may want to read this thread and see if it may help you a little......before you go any further:

http://www.jeepgarage.org/f183/oxyge...mer-20300.html

phottomatt 09-06-2013 08:36 AM

Re: O2 sensor: Location and testing
 
Quote:

Originally Posted by jeepgcoman (Post 887565)
As you can see by the testing instructions, this won't be a picnic. Generally, testing the sensors is more trouble than it's worth. If you do any testing, the best way is to find some sort of millivolt monitoring device. I use my on board DashHawks on both my vehicles. Testing with a meter at the sensor would not be fun on a hot exhaust, with the engine running. If you have no good, easy way of testing them, and you suspect them to be your problem, IMO, just replace them. That's not so easy either. Total cost of the 4 sensors should be no more than ~$125. You may want to read this thread and see if it may help you a little......before you go any further:

http://www.jeepgarage.org/f183/oxyge...mer-20300.html

Thank you for the info, something is going on though. It runs good but not quite right, gas mileage is a hair low and I suspect there might be an exhaust leak because it just doesn't sound right, doesn't sound like other GC hemis. Thanks again.

jeepgcoman 09-06-2013 10:11 AM

Re: O2 sensor: Location and testing
 
If you have an exhaust leak before the front O2 Sensors, you'll run rich....how much depends on how big the exhaust leak is. I had a pretty big header flange leak on a long trip and it cost me at least 3 mpg, and maybe more. Had to drive it ~900 miles that way, as no one wanted to tackle the repair job. Let us know what you find.

phottomatt 09-15-2013 06:42 AM

Well I could not find an exhaust leak, might be a very small one somewhere around the headers but can't tell. Guess I'll move on to the O2 sensors.

From Xparent red on the Wicked

Frango100 09-19-2013 11:19 AM

Re: O2 sensor: Location and testing
 
If you have an Android phone, you can install the app Torque on it and buy a cheap bluetooth dongle for the wireless connection with the jeep. You can then read the O2 sensor volts. The voltage indication goes normally from 0.2V up until 0.8 V and should be jumping up and down for the 1-1 and 2-1 sensors ( both upstream sensors, which are the main inputs for the fuel injection fine tuning).
The nice thing of the Torque app is that you can see many live data info, see DTC´s and reset DTC´s and check engine light. There is a free version with some reduced possibilities and a paid one with some more possibilities.

phottomatt 09-19-2013 11:51 AM

Quote:

Originally Posted by Frango100 (Post 896250)
If you have an Android phone, you can install the app Torque on it and buy a cheap bluetooth dongle for the wireless connection with the jeep. You can then read the O2 sensor volts. The voltage indication goes normally from 0.2V up until 0.8 V and should be jumping up and down for the 1-1 and 2-1 sensors ( both upstream sensors, which are the main inputs for the fuel injection fine tuning).
The nice thing of the Torque app is that you can see many live data info, see DTC´s and reset DTC´s and check engine light. There is a free version with some reduced possibilities and a paid one with some more possibilities.

Sweet, I'm a tech junkie so this is right up my alley. Thanks.

phottomatt 09-28-2013 03:28 PM

Re: O2 sensor: Location and testing
 
OK got Torque hooked up and took a couple videos. The top 2 gauges are sensor 1, the bottom 2 are sensor 2. I'm pretty sure both sensor ones are acting correctly, bouncing back and forth from roughly 0 to 1 but sensor two I'm not sure. When I first start up the sensors are at 0 and after the vehicle runs for a minute or so they come up but once in a while they will drop to 0 again. take a look and see if any of you guys know whats going on. Oh yeah the big gauge on the right is the tach in case you didn't already figure it out.
Take 1
Take 4

Frango100 09-29-2013 07:45 AM

Re: O2 sensor: Location and testing
 
The 1-1 and 2-1 sensors are acting ok indeed. They constantly change the voltage, indicating the air fuel mixture is being fine tuned all the time.
The 2-1 and 2-2 sensors (the after cats) are indicating the catalyst efficiency. Don´t know why they stay at 0V in the beginning, but lateron they act normal by being almost steady. When the catalyst efficiency goes down, the after cat sensor voltage starts fluctuating more and more until it equals the before cat voltage. But before this happens a fault code will be set by the PCM to show that the cat efficiency is low.

phottomatt 09-29-2013 08:56 AM

Quote:

Originally Posted by Frango100 (Post 901227)
The 1-1 and 2-1 sensors are acting ok indeed. They constantly change the voltage, indicating the air fuel mixture is being fine tuned all the time.
The 2-1 and 2-2 sensors (the after cats) are indicating the catalyst efficiency. Don´t know why they stay at 0V in the beginning, but lateron they act normal by being almost steady. When the catalyst efficiency goes down, the after cat sensor voltage starts fluctuating more and more until it equals the before cat voltage. But before this happens a fault code will be set by the PCM to show that the cat efficiency is low.

That's what I was hoping on the one hand on the other I now have to continue the search for my poor fuel efficiency.
Thank you.

From Xparent red on the Wicked


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