Dave my fuel trims have been a little high like in the 4 and 8 range for each bank. Should they generally be better than that?
Yes, they should be better. I shoot for zero, but that isn't always possible due to the condition of the engine, state of tune, components, etc. Any way you slice it, 8% is high. A positive number indicates that the ECU, based on the information provided by the O2 sensor, is adding fuel. Hence, you have a lean condition.
I had heard they should but i thought maybe because of the group m and cappi twin valve it might be off a bit.
Ah, no...not to the degree that you're off.
Short terms always hovers around 0 for both.
Interesting. I presume that this is at idle. I would check at 1500 and 2500, as well.
Fuel trim gives us tremendous insight on what's happening when the engine is in closed loop., However, it does not tell us what's causing the addition/subtraction of fuel. This can be caused by many different factors. Were the adaptive values reset at the last major? If not, reset them now and see where your fuel trim levels go.
If you create an artificial rich condition (propane enrichment) or pull a vacuum hose (lean condition) you should see both a rise or fall in front O2 sensor voltages as well as a corresponding (immediate
) change in STFT levels. If you don't, it's time for new, genuine Bosch, front O2 sensors....and none of the universal junk, either.