Loss of gas mileage.

SMOKESTAKR

MEMBER
2002 GMC YUKON
170,000 MILES

A short while ago I ran a fuel injector treatment through my fuel system with a full tank of gas according to the treatment instructions. Starting with that tank full my mileage decreased by 1 1/2 to 2 MPG. I historically have gotten 14 - 15 MPG local and 17 - 18 highway. I have always kept track of my mileage with every tank full because my fuel guage reads somewhat eratically. I maintain the vehicle accprding to manfacturers specs: oil changes, spark plug/air filter replacement, etc. There are no error codes displayed. Any ideas as to the cause. Thank you.

Wednesday, January 18th, 2012 AT 10:24 PM

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

Has a change to winter fuel historically caused a slight difference in fuel mileage, it should have. If the vehicles powertrain monitoring system is not noticing a problem, then parameters are considered to be within limits. A few things to check are, is the thermostat regulating temperature correctly, is the vehicle running a bit colder than it should? A scan tool that would show data, would show if there is any slight deviation in fuel trim, that may indicate a reason to be suspicious.

Was this

answer

helpful?

Yes

No

Wednesday, January 18th, 2012 AT 10:44 PM