My mpg is 6!!!


Asked by Jun 22, 2016 at 01:02 AM about the 1995 GMC Sierra 1500 K1500 SLE 4WD Extended Cab SB

Question type: Car Customization

I have a 1995 GMC seirra with a 6 inch lift and 35
inch tall tiers its got a k&n air filter and a 3 inch
exhaust with factory cat and a flow master muffler
that turns down with 2 2&1/2 inch pipes and I'm
getting a 6 mpg can anyone help me figure out why
my mpg us so bad???

4 Answers


What is your differentials gear ratio?




Ok 3.73's decent ratio for towing and oversize tires, should get you around 8 to 10 mpg. So may have some sensors out of specs, base timing is slow, fuel system too rich. I would start with the base timing, make sure the engine is at operational temp, shut off engine,disconnect the spout connector, restart engine and set base timing and then add 2 degrees, shut off engine and reconnect the spout connector. Checking the sensors will require an ohm meter and a sensor resistance chart to compare resistance with temps, a and each sensor will have to be manually checked, unless you have one of the old GM OBD 1 scanners, then you can check each sensor separately, and don't forget to check the O2 sensor for proper switching. Then test the fuel pressure just too make sure it is not too high. HTH


Ok. Thank you so much!

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