I have a 1998 GMC Jimmy 4.3L v-6 with 140,000 on it. It drives well, but gets horrendous gas mileage. I wanted to check to see if any codes are set to possibly point to a component that may be defective, hence affecting my mileage. I've replaced the plugs, wires, cap, and rotor. Didn't check the timing since I wasn't having any driveability issues. Can the data link be "grounded" to flash codes or do I need to have a reader? My 94 GMC P/U will allow me to ground and flash the "check engine" light if codes are set.
Do any other Jimmy owners out there have the same problem with mileage? Is this just inherent with this vehicle?
Any info or advice would be greatly appreciated. Thanks in advance. Andy