|
My Canyon has the same 3.73 rear axle ratio, and came with 225/75R15 tires. I am now running 235/75R15 tires, which gives me 1800 RPM at 55 MPH.
The factory service manual lists the following causes of poor gas mileage:
Faulty knock retard
Plugs - gaps, fouling
Cam timing
Fuel injectors - connected in correct order, flowing properly
PCM ground connections
Plugged air filter
Vacuum leak
Fuel pressure
Try setting your Scangauge to display MAP (manifold absolute pressure) and IGN (spark advance). My truck had the following readings yesterday at 70 deg F, 1800 RPM, and running 87 octane gas with 10% ethanol:
45 degrees at 7 lbs MAP
17 degrees at 10 lbs MAP
Yours should read the same. A bad knock retard could retard the timing 15 degrees, which would kill the mileage.
The FSM says that plug gaps are important for gas mileage.
__________________
06 Canyon: The vacuum gauge plus wheel covers helped increase summer 2015 mileage to 38.5 MPG, while summer 2016 mileage was 38.6 MPG without the wheel covers. Drove 33,021 miles 2016-2018 at 35.00 MPG.
22 Maverick: Summer 2022 burned 62.74 gallons in 3145.1 miles for 50.1 MPG. Winter 2023-2024 - 2416.7 miles, 58.66 gallons for 41 MPG.
|