fuel trim questions

[tsi2fly1991]

I just got my datalogger and I have a few questions about some Parameters I was wondering about the 02 trims what is rich anything above 100% is rich and anything below 100% is lean is that right? Another thing is low med high trims is the low trim for low rpms and is med for med rpms and high for high rpms. one more question when i logged my car at idle this is what i got so the o2 trims are they supposed
to move that much. Farther in the log it gets down to 66% and stays under
100 for few seconds than comes back up over 100 for a few seconds than goes right back down and so on
02 v 02 trim
0.57 122
0.43 123
0.27 126
0.18 127
0.12 129
0.1 130
0.1 132
0.08 134
0.08 136
0.08 138
0.08 140
0.08 141
0.12 143
0.22 145
0.39 147
0.63 144
0.8 141
0.86 139
0.86 136
0.84 133
0.82 130
0.78 127
0.75 125
0.71 122
0,63 119
0.45 119
0.31 122
0.22 123
0.16 125
0.12 126
0.1 128
0.08 130
0.08 132
0.08 133
0.08 136
0.08 137
0.14 139

 

[steve]

Not sure if you were logging O2 feedback trim or one of the fuel trims but O2 feedback really isn't too interesting to log generally and any log without rpm's is useless. You should also log injector pulse width if your going to look at fueling issues. If you datalogger calculates Duty Cycle any time it goes over 100% (and lower with some injectors being unstable running static) means you have just exceeded the capacity of your fuel system and additional fuel requirements calculated by the ECU will not be met causing the actual AF to climb.

Keep in mind that during closed loop you don't actually run rich or lean. The fuel trim numbers let you know how much the ECU corrected it's calculations to run at 14.7:1 AF based on the feedback from the O2 sensor. It can give you an idea of what might be happening once you go open loop and the fuel trims are no longer included in the injector pulse width calculations.

Steve

 

[CanadianTSi]

Anything above 100% means that the car is running lean so the ECU is adding fuel, anything below 100% means the car is running rich and the ECu is taking away fuel.