Poor gas mileage 5.3ls1/4l60e in a 1971 c10
#1
Poor gas mileage 5.3ls1/4l60e in a 1971 c10
Now that I have my speedometer/odometer working properly thanks to ls1nova and other members on this forum. I have noticed I am only getting approximately 10 mpg in city driving. I am running 5.3ls1/4l60e combo with no catalytic converter and essentially a basic tune on the PCM as it was purchased with a wiring harness from PSI. The truck has a 3:73 rear end and 28.7 inch diameter rear tires. From what I have read it seems like I should be getting at least 15 and upto possibly 20 mpg. I have not hooked it upto the scanner yet but I was hoping for some thoughts on possible causes. By the way I have not been driving aggressively.
#3
TECH Veteran
iTrader: (4)
10 mpg is almost unbelievably low, does it smell really rich? Also, how much have you driven it? How many tanks have you been through? I would run several of tanks of fuel through it and average them together since sometimes you can get more fuel in the tank at one station than at another station. Have you driven it on the highway and made sure the odometer is correct with the mile markers, or at least close since mile markers are not always super accurate. Also, yeah, verify that your tune is correct.