Hi. every one!
280 K windstar 2000, LTFT or Bank 1 remains 3 to 6. bank 2 remains -0.8 or 0.8. Remains same at high RPM 1500 But at 2500 rpm LTFT becomes normal near zero or 0.8 + -. Changed bank one upstreamO2 sensor no effect. No missing. Mode 6 shows no missing. Plugs and wires are 2000 KM. No CEL. No rough idling. No drive-ability problem. No oil leakage. no effect on spraying gas on engine. 9MPG in city and 14 on freeway. engine coolant and engine oil is not loosing. Regularly change engine oil and transmission oil.Any idea???