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brentsten
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Feb 3, 2013, 11:01 AM
Post #1 of 9
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Is this a failing o2?
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First post here! I've tried the usual automotive forums that I subscribe to, but haven't had any luck. I found this forum in a google search, so I figured I'd give it a shot and see if anyone can help diagnose this issue.
I have a 2009 Pontiac G8 GT. I'm using HPTuners to scan the vehicle's sensors. If you're not familiar with the software, you can just skip to the end; I've posted a video of the scan measuring live sensor outputs. Basically, I'm looking at the o2 sensors. Bank 2 seems to be doing its normal switching, but bank 1 is very erratic. I'm wondering if the o2 sensor is failing.
O2B1 = o2 sensor bank 1
O2B2 = o2 sensor bank 2
WB LC1 = Wideband o2 sensor bank 1 (pre-cat)
Everything is connected as it should be; I've tried jumpering power straight from the battery and ensured I have good ground connections. After connecting my wideband sensor (gauge and laptop) I was reading right around 14.7 AFR plus or minus a few decimals. Driving part throttle around town I'd see down to the 12.xx range, but hardly ever touched 15, seemed perfect for a baseline. I stopped to get gas and after restarting the car, the readings were extremely erratic. I was reading anywhere from 10 to 21 on the gauge and in software and they weren't strung out either; it was instant and sporadic. My first thought was bad gas, but the car seemed to run and idle perfectly normal. My next thought was a static discharge from the pump might've shocked something in the system. I let the car cool down overnight, and went out today for fresh readings. The factory narrowband o2 sensor on bank 1 seems out of whack. It does it's normal switching high and low, but while doing it the voltage jumps high and low (if that makes sense). The wideband is installed on Bank 1 also and seems to correlate the same readings as the narrowband. I took a video of the scan, if you are familiar with the . I'm thinking the narrowband is shot and the reason the wideband was picking up a correlation was from the fueling adjustments the ECM was trying to make. Does this make sense?
http://www.youtube.com/...&feature=youtube
(This post was edited by way2old on Feb 3, 2013, 11:35 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 3, 2013, 11:30 AM
Post #2 of 9
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Re: Is this a failing o2?
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It looks to me like that sensor is doing exactly what it's supposed to do. Your software is too slow to process even half of the actually changes taking place. The more times it goes up and down, the better the system is working.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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brentsten
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Feb 3, 2013, 12:59 PM
Post #3 of 9
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Re: Is this a failing o2?
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If you watch bank 2, that sensor seems to be oscillating normally. Bank 1 is oscillating overall, but there are a lot of spikes between the peaks, which seems abnormal. The software's resolution isn't as fast as the sensor, but its fast enough to read normal oscillations. I'll upload a video of it being graphed as well for a better look.
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Hammer Time
Ultimate Carjunky
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Feb 3, 2013, 1:04 PM
Post #4 of 9
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Re: Is this a failing o2?
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Unless you have a lab scope, you are looking at processed data and you are not seeing even half of what is happening.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
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Feb 3, 2013, 1:04 PM
Post #5 of 9
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Re: Is this a failing o2?
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You aren't really using that software for the way it was intended........
You are trying to take the place of one of the computers moniters to check a system.....The biggest problem is don't have all the parameters for monitering that circuit and more importantly what is a reason for a fail...
For a lot of the problems you need to be looking at the fuel trims and what they are doing.....
The PCMs do a pretty good job monitering these system and there are a lot of individual perfomance codes for failing O2 sensors......
If for whatever reason you need to moniter O2 voltage, you really need to graph the data, looking at a live feed doesn't give you the whole picture to what is going on....
Can your software graph data?
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brentsten
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Feb 3, 2013, 2:09 PM
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Re: Is this a failing o2?
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It's capable of measuring any PIDs defined in the ECM. Long and short term fuel trims were on the gauge display in the video, but partially cut off at the lower right. The software can display gauges, graphs, tables, or histograms. Here's a video of the same log in graph form. Now I'm wondering if bank 1 is switching too fast or if bank 2 is being lazy.
http://youtu.be/OyuUJHF8nKQ
(This post was edited by brentsten on Feb 3, 2013, 2:10 PM)
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Discretesignals
Ultimate Carjunky
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Feb 4, 2013, 6:08 AM
Post #7 of 9
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Re: Is this a failing o2?
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Is this storing any trouble codes?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Sidom
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Feb 4, 2013, 11:00 PM
Post #8 of 9
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Re: Is this a failing o2?
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Without knowing a brand & just looking at that pattern you would think that one of the O2 is getting a little slow but with O2s or really a lot of the other sensors, you can't just go off of graphed data, especially if there are on codes or pending codes....
The PCMs are pretty good at spotting troubles like this & there are even specific DTCs for them.....
Off that pattern.....Yea it's possible you have an O2 going bad & yes sometimes things will fail on systems that should set a code & don't....It's just the nature of the game.....
On this one.....Your next step would be to test the O2 with a scope using the propane enrichment method.......You would hook up your scope, add proprane & both O2 would go rich (high voltage) with no crosscounts. Once the proprane was remove, you would get crosscounts again. You measure the distance of the 1st crosscount, between 1.75mV & 8.25mV would have to happen within 100ms or less, any more the sensor is slow & would need to be replaced....
Personally if you aren't having any problems, then I don't think the sensor is bad..
If it was you would have a code or the fuel trims would be off try to compensate for the bad sensor.
It's late & I just took a quick look but from what I saw, the trims looked good....until the LTFTs get into the midde teens for more that a few seconds, there isn't anything going on.....
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brentsten
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Feb 5, 2013, 6:21 AM
Post #9 of 9
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Re: Is this a failing o2?
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The ecm hasn't set any codes. The main reason I was curious in all of this was after I connected a wide range air fuel sensor and my readings were from one end of the spectrum to the other. It was my understanding that a wide range sensor shouldn't switch like a narrow as they are linear.
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