Chevrolet Repair: blazer likes to drink, lean mixture, blazer s10

Question
Hi i have a 1993 blazer s10 i changed plugs and wires and and it gets about 10 miles a gallon, a code reader tells me it needs a oxygen sensor but would that make it that hard on gas it also has a little miss only when i drive 100 km/hr or less. could you please help. thank you in advance.

Answer
HEy,

  You need to see what the 02 is up to.  If it is reading a rich mixture that exists that is why the code was there and you can backtrack looking for the cause of the rich mixture. If the 02 is reading a lean mixture that is actually rich the computer will keep adding fuel until the fuel trim maxes out.  You would be blown away at how much a pcm can add if the 02 is stuck lean.

Wayne