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hi,
Yesterday, i took off my one month old/1700miles spark plugs(OEM volvo) and noticed that they are burned black on the tip instead of gray. Is this an indication of lean or too much gas mixture? i changed the, oem plugs, rotors, caps, wires, serviced TB, new flame trap, mobil syn blend oil, new air and fuel filter. My gas mileage consumption is 25mpg on the freeway and a bad 14mpg on the street, esp when wife is driving (lead feet?). I don't burn oil so far; but i noticed black soot on my exhaust. I don't have bad codes for O2 sensors. tried to replace my vacuum hose with ordinary hose instead of OEM ones, although i don't notice any vacuum leak . by the way how do we determine vacuum leaks? should i change O2 sensors and install oem vacuum hose?
thanks in advance for inputs.
94 850 wagon n/a 192K
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