Newly installed Wideband: 10:1 at idle?!
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This is a discussion on Newly installed Wideband: 10:1 at idle?! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I just completed the install of my AEM EUGO. I used the bung that comes on my downpipe (pretty much ...

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    Newly installed Wideband: 10:1 at idle?!

    I just completed the install of my AEM EUGO. I used the bung that comes on my downpipe (pretty much right behind the turbo). When I first started the car up, it read as idling at about 10:1 AFR. That seems dangerously rich for idle. I was pretty much afraid to keep the car running at that AFR. I have a COBB off the shelf map with a VF39, and TBE. Only thing I can think of is that the map I have is for 91Octane, but I am currently running 93octane fuel, but even still, I can't imagine that causing the car to run that rich. Any ideas? Maybe the sensor is bad?

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    Good news, everyone! xxxxxxxAnub1s's Avatar
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    Did you calibrate the O2 sensor first?
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    I thought the AEM UEGO came pre-calibrated? At least that is what the instruction manual says. Am I missing something here?

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    UPDATE: I know the factory sensor isn't accurate, but I cross-referenced what the UEGO said against my Cobb AP. First, the AP said I was idling at 14.7AFR, then 20 minutes later it said I was idling at 20.2 AFR! These were both from a cold start, so the RPMS were at about 1300...

    Faulty O2 sensor? I am the second owner of the car, so I couldn't comment on if they are the originals or not. Vehicle has 80k miles.

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    Good news, everyone! xxxxxxxAnub1s's Avatar
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    Quote Originally Posted by pfcrangel View Post
    I thought the AEM UEGO came pre-calibrated? At least that is what the instruction manual says. Am I missing something here?
    Right you are, apologies. Could very well be that your factory sensor is faulty. Cross check the values from your AP and from the UEGO sensor. Does the UEGO change values comparable to how the stock reading does? If the UEGO sensor is reading just one number the whole time, something is up with the unit itself.
    Cody
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    UPDATE: I cleaned the MAF, and it didn't do any better. I also let it heat up to operating temperature, and it started to idle at a slightly leaner 11.5 range.

    I also tried idling it with the front o2 sensor unplugged, the car idled rougher, but at an even leaner 13.5 range, much closer to normal. I threw a code P00301 right after I unplugged the o2 sensor,naturally, but it didn't turn off right after I plugged it back in. Is this to be expected? Or maybe my o2 sensor is shot and unplugging it just triggered it turn on. I know it will turn off if I reset the ECU.

    couple questions:

    Why would the car idle leaner with the o2 sensor unplugged?

    What does the COBB AP use to monitor AFR? My AP read at 14.7 one time, and then 21.0 another time. Could this also indicate a fauly o2 sensor?

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