MPG and 02 Sensors on 5.7 Vortec

[Austin Orth]

I have a 1999 K2500 regular cab with the 5.7 and 4L80E transmission, 285s for tires. I got 14mpg bringing it home, which was about 250 miles. I've been driving it around and I'm getting about 9-10mpg. I have read that an exhaust, cold air intake, and new 02 sensors. I plan on replacing all of the 02 sensors so I was wandering how many upstream and downstream sensors there? And is there any other ways to improve my fuel economy? Thanks

[Jsdirt]

Plugs, wires, cap, rotor, clean or new air filter, and some synthetic oil for the entire driveline. After a several mile drive, check brake rotor temperatures - any hot ones that stand out from the rest are dragging  / hanging up. Then check tire pressures to be sure they't not low as well.

[KARNUT]

And, if it doesn’t have stock size tires that would help. How many RPMs you’re turning at highway speed? Could have a towing gear.


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[CamGTP]

Get lighter, smaller tires.

 

And a 1999 will have 4 o2 sensors. Two upstream and two downstream. Get OEM parts only, so Delco/Denso is likely what they will be. No aftermarket stuff.

Edited April 17, 2021 by CamGTP

[Austin Orth]

On 4/15/2021 at 9:09 PM, Jsdirt said:

Plugs, wires, cap, rotor, clean or new air filter, and some synthetic oil for the entire driveline. After a several mile drive, check brake rotor temperatures - any hot ones that stand out from the rest are dragging  / hanging up. Then check tire pressures to be sure they't not low as well.

Will look into that, thanks!

[Austin Orth]

11 hours ago, CamGTP said:

Get lighter, smaller tires.

 

And a 1999 will have 4 o2 sensors. Two upstream and two downstream. Get OEM parts only, so Delco/Denso is likely what they will be. No aftermarket stuff.

I don't know if I want to change my wheels and tires, they really do look good on the truck. I do appreciate the info on the o2 sensors, thanks.

[Austin Orth]

On 4/16/2021 at 7:36 AM, KARNUT said:

And, if it doesn’t have stock size tires that would help. How many RPMs you’re turning at highway speed? Could have a towing gear.


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I was running about 2000 going 70.

[KARNUT]

I was running about 2000 going 70.

The gears not the issue.


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[grampadirt]

Know anyone with a good scanner? I'd check the fuel trims first,they'll tell you alot.Check the MAF sensor,might need a cleaning.Got a clean air filter?Does it have the correct spark plugs?