oxygen sensor will be the o2 sensor's voltage, varying between 0 and 1. STFT is the short term correction the ECU is applying to reach 14.7 afr at that moment based on o2 sensor feedback. Values range from -25 to +25.

 

i cant find the o2 sensor voltage can you tell me which one is it?

 

oxygen sensor (1)

 

Also are you positive you do not have an exhaust leak? An exhasut leak before the wideband O2 sensor would genereate a "lean" condition FYI...

 

true, could be getting enough flow at cruise and full throttle runs to read properly and only really leaking bad at idle. OP you could varify this by looking at your fuel trims in evoscan. If you short term fuel trim is pegged +12% or 25% (can't remember where it maxes) at 17afr at idle then your probably idling in the right afr range and just getting a bad wideband reading.

 

Max/min STFT is +/- 25.
Max/min LTFT is +/- 12.5

 

i took the datalog at idle but it fails to upload over here....any tips on how to upload?

its a 2mb file.

 

i'll re-tighten the nuts and see what happens...

 

open the log in excel or openoffice calc and take a screen shot of it and post the pic. Doesn't need to be a huge log if it's just idle.

 

ok here are the pics of the data log..

tell me what do you see, do i need to replace the front o2 sensor?

 

You will have to log fuel trims and post a file where we can see what is going on... that screenshot did not show fuel trims...

 

ok i'll data log again and report back.

 

Put it in a .zip archive, then you'll be able to upload it.

 

To me, it looks like your front o2 is on it's way out. Your timing at idle hits a low of 6* and a high of 18* with your o2 voltage going from .15xx to .8xxx. Does it have a rougher idle than usual, or sound like it lopes a little more than usual with the cams?

My car doesn't have cams but, if you heard it at idle and didn't know the car, you'd think it did have cams. I'll be replacing my o2 this weekend, I'll post a log of my idle so you can compare tonight.

 

It's normal for the sensor's reading to vary from low, to high, back to low, etc. The key is that if you plot o2 voltage vs time, it should look like a fairly regular variance, not one that is seemingly random.

Try logging JUST o2 sensor reading (to get the best sample rate). Then create a line chart in excel of o2 sensor voltage relative to time. Post that up.