i have a 1997 blazer, 4.3 vortec,....had codes in system, i replaced the bad sensors...codes gone but my gas mileage is around 9-10mpg.
engine idles and runs fine but why the bad mileage...i'm at a loss here, any help would be greatly appreciated. also replaced dist. cap, wires and plugs.

 

Have you done any mods?

Fluids need changing?

 

What codes were present? When was the last time you changed your plugs and fuel filter? how's your foot? Air filter?

-OSS

 

no mods-stock, o2(2) ,and map sensor, replaced.new plugs, wires, dist cap, rotor and air filter...light right foot..lol..fuel filter replaced before sensors...about a month ago...all fluids replaced when i bought it used 3 months ago, now i know why it was so cheap. ive never had this problem with a chevy before.

 

If you haven't already, try resetting the computer then drive it for I think 70 KMS/43.49 miles and let the computer retest all the sensor, then see what kind of mileage you get.