bad o2 readings

[foreverinvayne]

Okay.. I am using my datalogger(palm m100 with the mmcd program) to tune my maft setup that I just installed and I am trying to follow the basic directions. I am confused on one thing.. It says to adjust the aux/base based on what keeps the total trim between 80 and 100%. Well, i just did a run like it told me to; steady 35-45mph. Well, my question is this... is the total trim basically what it says on my datalogger as o2trim or what? it says on the paper that the total trim is the product of active fuel trim and the o2trim. Well... that kinda doesn't make any sense to me right now. can anyone explain this? And also... my o2 readings are running really slow right now with it going between 35% and 150%. But it's not quick at all... it stays real far down for a few seconds, then moves up to about 80% for a few seconds, then well over 100%. Well, I guess my main concern is what EXACTLY do i use for total trim?

 

[spyderturbo007]

I would assume that they are talking about fuel trims and not O2 trim.

 

[foreverinvayne]

well, here's another question... is above 100% too rich or too lean?

 

[spyderturbo007]

If you are above 100% with your fuel trims, the ECU is adding fuel. Below 100% and the ECU is removing fuel. It's not that they are necessarily rich or lean, but it is what the ECU is doing with fuel delivery.

If for some reason the car is indeed running lean for some reason, the ECU will begin to add fuel to compensate and vise versa. So you really can't say that it is actually rich or lean, but it's the ECU's intrepretation of the situation.

Now, if we are assuming that this is being caused by a bad O2 sensor (i.e. there is something causing a "false lean") then the AFR (FT >100%) would indeed be rich.

Am I making sense or just confusion people??? Man, I really tend to ramble.

 

[foreverinvayne]

I shoulda phrased that better... above 100% is that the computer is SEEING a lean condition and is adding the fuel. not that the car is actually running lean. It does get confusing... but anyways... thanx. I did find another link that helped me out a lot when tuning the maft. I guess it woulda been better for me to disconnect the battery and let the ecu reset itself before i started logging and wanting to tune . That's the biggest part i forgot about.