Quote:
Originally Posted by kc15842
Great subject with the head gasket and the approach to trouble shooting.
You mention the differences between bank 1 and 2. I'm very green interpreting this information. What exactly is this showing us?
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What Fuel Trim Values Should Be
Ideally, the STFT and LTFT should be within a few percentage points of zero when the engine is idling or being held at a steady RPM. Remember, STFT can bounce around quite a bit as when you suddenly snap open the throttle or decelerate. But LTFT can tell you if the average fuel/mixture is running rich or lean.
Good LTFT values should be as close to zero as possible, though they can range from 5 to 8 percent depending on the condition of the engine. If the LTFT is getting up around 10 percent or higher, it usually indicates a problem that needs to be diagnosed.