1999 5.2 magnum Fuel Mileage

Hi! I have a 1999 dodge ram 1500 5.2 (318) magnum, ST extended cab 2dr 2wd. I am getting about 11.5 mpg and i'm wondering how i could increase this without making any major upgrades, i've read that a cold air intake and a new exhaust might help but i really have no knowledge on this sort of thing so any advice is appreciated. Thanks in advance!

A CAI wont do anything for your fuel economy, our air intakes are as good as you'll get without a true ram air intake. As long as you have an exhaust, you'll be fine.

11.5 city? or highway? city, thats about right for a truck that needs a tuneup, but highway thats a bit low.

Good places to start is making sure the correct viscosity oil is being used, either 10W-30 or 5W-30. Make sure the spark plugs are the copper type if you're going to replace them, plug wires, cap and rotor, seafoam in the gas, run some through the intake.

How fast do you burn oil, if any?

Slightly restrictive muffler setup to match the restrictive intake manifold and heads has shown good results for highway usage. My own for example, full stock engine and just a Flowmaster 50 series cat back exhaust, with stock tire size i managed 19.5mpg on a cross state trip and 17 coming back. Good air pressure in the tires, ethanol free 87 octane fuel, no wind, cruise at 65, no stops.

Mine example is rare, though guys regularly report 16s with similar setups. This is highway mileage mind you. In town, good luck.

Another suggestion: $5 obd2 dongle and TorquePro app for smartphone. This allows you to monitor your fuel status meaning whether it's in closed loop or open loop. Closed loop the oxygen sensor attempts to maintain 14.7:1 a/f ratio whereas open loop goes off preset conditions in the pcm. Slightly rich preset conditions. Above 23.5% throttle input goes into open loop, you can monitor throttle percentage as well

98 4x4 Ram ext cab (4door) 5.9 with Shell, stock tire size at a good tire pressure, 70-80mph with a full load of people and gear 300 mile round trip I managed to average 16mpg.

Do the basic stuff first, air filter, plugs, cap, rotor, wires. Then I would look into the exhaust side of things and make sure its not plugged up.

In the city driving style will have the most impact on mpg, some get 10, some like myself get 14, but my city is different than others, not much stop and go here.

I average 11.5 city, and 13 highway, my exhaust runs from the catalytic converter to a glass pack and i just put on an 18" extension to a down pipe havent had it on long enough to see if that helps or not. I run 10w-40 because the truck burns through 10w-30 like a cigarette.

Check out the plenum thread at the top of the engine and performance section. Poor gas mileage as well as oil consumption are two major signs of a plenum leak.

I run synthetic 10w-30 and dont lose a drop.

If you are losing oil 9 out of 10 times its the plenum. Stick a magnet stick down your throttlebody and if it sticks to the bottom of the intake you have a steel plenum and more than likely its leaking.

You could also pop the throttle body off and look for excess oil in the intake.

Its a very common problem with these motors.