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Are my narrowband oxygen sensors bad?
Symptoms:
1) Put the car in closed loop and it chugs and dies within a couple miles (goes rich rich rich). Car is tuned pretty much perfectly in open loop and runs like it, too. Not using LTFTs.
2) Mv's are commanded to switch across the board at 475 (any better suggestions for long tube headers?) but when cruising down the road at, say, 1500 RPM one stays right at 580 and the other around 650..... What does that mean?
I have two new O2 sensors sitting in the car for install today at lunch time....I don't want to put them in if I don't need them, but given the .5 differential in AFR over 20 degree temp swing in OL, I want to run closed loop again. And just as a side note, I did run C12 for a month or so while dialing in my nitrous, but now I think that was a huge waste as I will just run MS109 when I spray and save my sensors....
Anyways, any help? Thank you....
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Advanced Tuner
Just one question I have. Do you fully trust the wideband you are using? Like how rich are we talking? Something like -25 stfts??
Got a tune or a log to post?
Last edited by KLUG'S SS; 09-09-2010 at 07:58 AM.
2017 Silverado LTZ
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I am watching the nb voltages in open loop. it doesn't run well enough or long enough to get any good stft numbers. i trust the wideband 100%, mostly because it's all I have, but also because the car is flawless in open loop and will literally foul the plugs very quickly in closed loop. i can't post anything from work, sorry....
what about the non-computer read symptoms? indicative of o2 sensors?
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Tuner
Post your tune, log and config files when you can.
your O2s and wideband may not be agreeing, which means one of them is off. The culprit is usually the wideband, and it's probable to notice if your VE values are too high for LTs alone.
Do you have any other mods?
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408 ci w/all the trimmings and nitrous. 715 rwhp.... car started acting up after I sprayed on some c12. i already replaced them a few minutes ago. we'll see!
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ok well just as an update, the car actually ran with new 02 sensors.... but it WAS tuned rich also off my wideband. therefore, I scaled the transfer function to what seemed to be close enough and tuned off STFTs. Car is running good in closed loop now and over extended driving time, the STFTs are close to AFR Error. I can move on with life.
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