o2 readings? .900+ rich or lean?
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
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From: Troy, AL
It could be either but there's a better chance that it's a bit on the rich side for optimum NA times. The factory O2 sensors aren't so great for giving WOT fuel/air readings...not good at all. A rough idea is all.
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
There's no way to know that they're perfect without track testing...not even a wideband O2 sensor can tell you were your best MPH is going to be...much less our crappy narrowband O2s. On one car .900mv could be perfect, on another it could be lacking a MPH or more in the 1/4.
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
There's no way to know that they're perfect without track testing...not even a wideband O2 sensor can tell you where your best MPH is going to be...much less our crappy narrowband O2s. On one car .900mv could be perfect, on another it could be lacking a MPH or more in the 1/4.
on my car and my friends ss about 900mV to about 915 seem good for the car, for example no pinging.....i hav ebeen save aroudn 885-905 and if they were all consisten this would be a good BASE but they arent all consistent....if you tune between 890 and 920 you would be safe where u woudlnt be running too lean or rich....from what i was told....but like everyone says to get it dialed in u need to use a wideband...
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Teching In
Joined: Nov 2003
Posts: 11
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Originally Posted by Texas Terminator
technically kind of on the rich side. use it as a baseline ONLY! use a wideband AND read your plugs.
Thanks in advance! 
11 Second Club
Joined: Jul 2002
Posts: 1,426
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From: Beaver Falls, PA
Originally Posted by azgasser
I am reading .930 to .950. I feel that this is rich, and I am having a Wideband O2 done on Saturday. Anyway, how do you read the plugs? Just installed NGK TR55's on my 03 Vette. Have the originals still, what should I look for Thanks in advance!
Thanks in advance! 
TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
It does not mean your running rich all the time,
it could be the engine was running lean and the PCM is driving the injectors on longer to drive the fuel trims back down.
Best bet is to look at the short term fuel trims since the engine functions off them and also compare the long term values to see what has been going on over a long period of time.
O2s are after the fact, thus fuel trims can be too lean and PCM is doing its job by going richer for a bit to rid the lean state.
it could be the engine was running lean and the PCM is driving the injectors on longer to drive the fuel trims back down.
Best bet is to look at the short term fuel trims since the engine functions off them and also compare the long term values to see what has been going on over a long period of time.
O2s are after the fact, thus fuel trims can be too lean and PCM is doing its job by going richer for a bit to rid the lean state.
Teching In
Joined: Nov 2003
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My LTFT's now after dropping my PE to -3% by using the Predator are now in the -2 to 0 range and my O2 sims are .900 to .915. I think I am heading in the right direction. Getting wideband done on Sat. but want to be close when I get there so I dont waste much time dialing it in.
11 Second Club
Joined: Jul 2002
Posts: 1,426
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From: Beaver Falls, PA
Originally Posted by azgasser
Here are the pics of 4 of my plugs, from the looks, they inidicate that I am running rich. I am adjusting my PE more neg today. Will post my new O2's and LTFT's #. Thanks for all your help. 
