Horrible Gas Mileage with Lying Fuel Econ Computer

[TheEnder]

Hey everyone,

My dad has a 2016 RAM with the 5.7/8 speed and since i work on my truck all the time he asked me for some help.

So, his truck is going through gas like it’s literally nothing. There’s only 50K on the engine, it doesn’t tap, and it sounds good. Trans shifts kinda hard but i don’t know if it’s because it’s programmed differently than the V6 8 speed.

He got a full tank of gas and i told him to reset the trip computer and write down an avg of how many miles the fuel economy gauge said there were until empty, which was around 390. He got back from around an hour drive, trip computer said that he drove around 50 miles and the truck was already down to half a tank from being above the F to begin with.

The fuel econ meter is saying he’s getting around 15.3 MPG average, which can’t be right.

I pulled out alfaobd to check spark advance, even though the plugs don’t need to be changed, and i don’t know if this is correct or not but it was pulling almost -70 degrees of spark advance.

Any help?


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[caulk04]

Have him go full it back up and see what it actually takes. Seems I've heard of issues with the fuel level sensor...

A half tank in 50 miles is in the neighborhood of 4mpg. You'd know if it were running that rich.

 

[ToxicFire]

Have him go full it back up and see what it actually takes. Seems I've heard of issues with the fuel level sensor...

A half tank in 50 miles is in the neighborhood of 4mpg. You'd know if it were running that rich.

Wow I agree 4mpg is insane. My summer blazer with 24,s gets 11 and I complain I could not imagine 50 miles for half the in the ram.

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[TheEnder]

Wow I agree 4mpg is insane. My summer blazer with 24,s gets 11 and I complain I could not imagine 50 miles for half the in the ram.

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I asked him to come back over, which he might no be able to do until tomorrow.

I’ll let y’all know the info.


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[Ohio5pt7]

I'm getting 16.5 right now with wheels that weigh in @ 120+ each. So short story thats horrible

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[Travelin Ram]

Smell any gas? A leak would drain the tank and trick the computer because that gas isn’t going through the injectors.

If it’s super rich it’ll be smoking black and I’d expect codes.

Some vehicles a faulty coolant temp sensor keeps the engine in rich warming mode. Unlikely, because that will show up in the displayed MPG.

 

[TheEnder]

Smell any gas? A leak would drain the tank and trick the computer because that gas isn’t going through the injectors.

If it’s super rich it’ll be smoking black and I’d expect codes.

Some vehicles a faulty coolant temp sensor keeps the engine in rich warming mode. Unlikely, because that will show up in the displayed MPG.

He has been complaining about lack of power, and he talked about black smoke around a month or so ago but i thought nothing of it. No codes are stored in the PCM but in the BCM theres codes for one of the parking lights being out which is probably unrelated.

No leaks anywhere and can’t smell gas with the hood open either.


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[G-Ride990]

Hey everyone,

So, his truck is going through gas like it’s literally nothing. There’s only 50K on the engine, it doesn’t tap, and it sounds good.

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On the engine? Was the engine replaced at some point?

 

[TheEnder]

On the engine? Was the engine replaced at some point?

Engine never replaced, just putting it out there that there’s only 50K on it.

Everything on his truck is original, except for floor mats maybe.


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[alpinegreenneon]

Are the brakes possibly dragging? See if any wheel is unusually hot after a 15 minute ride.

 

[16Ram4x4]

Complaining about lack of power and black smoke I would suspect bad CO sensor/s and a clogged catalytic converter/s.
Also be sure the thermostat is good along with the coolant temperature sensor

 

[TheEnder]

Are the brakes possibly dragging? See if any wheel is unusually hot after a 15 minute ride.

He came over tonight just real quick on his way back from getting food and i looked under the truck.

Long story short, the bottom left front left brake caliper screw was gone, and the caliper was hitting the front left inner rim.

Not sure if that would actually effect anything fuel economy related, but it’s sitting in my driveway so i can fix it tomorrow. He took my truck home.


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