Decreasing fuel mileage

[Firemansac]

Hey folks new to the forum here and have what I hope is a simple question and answer. I have a 2011 2500 mega cab 4wd with the 6.7 and since I live in california(don’t hate me) it has all of the stock emission bs on it. Lately I have noticed my fuel mileage is starting to decrease. Today it dropped to 9.8 around town. Not running a bro dozer set of tires nor do I have a shell on it. Basically it’s a grocery getter except when I tow a dump trailer or pick up material for home improvements. The only thing that isn’t stock is the transmission which **** the bed at 89,000 miles. I currently have 121,232 on it. Any ideas as to why my mileage sucks and is getting suckier? Thanks for the help in advance,

frank.

 

[p-Bar]

Welcome to the Forum. Being a grocery getter and not getting on the open road I bet your DPF is clogged. Need to run it down the freeeway.

 

[Firemansac]

I should clarify that. I do drive the freeway I just don’t do significant towing but I will definitely try hammering down on the freeway as well. I’ve had messages in the past telling how full the filter was and to regen it. It hasn’t shown that lately

 

[cerberusiam]

Hammering it on the freeway is just going to waste fuel and hurt already bad mpg. You need higher cylinder temps for an extended time to do any good, like in hours at a time under a heavy load. It is hard to get extended heat into a 6.7 anyway and the stock emissions just doesn't allow it to happen.

Do you run an additive package? That is probably the easiest and cheapest way to help clean up carbon deposits and keep them form forming. A good strong fuel conditionr plus extra lube will go a long ways towards helping DD problems.

Is it possible you are having transmission issues also? A slipping trans or lockup failures can have a dramatic impact on mileage, especially DD around town.

 

[Firemansac]

Hammering it on the freeway is just going to waste fuel and hurt already bad mpg. You need higher cylinder temps for an extended time to do any good, like in hours at a time under a heavy load. It is hard to get extended heat into a 6.7 anyway and the stock emissions just doesn't allow it to happen.

Do you run an additive package? That is probably the easiest and cheapest way to help clean up carbon deposits and keep them form forming. A good strong fuel conditionr plus extra lube will go a long ways towards helping DD problems.

Is it possible you are having transmission issues also? A slipping trans or lockup failures can have a dramatic impact on mileage, especially DD around town.

 

[Firemansac]

I have just started running injector cleaner and cetane boost I was thinking I might need to have my dpf baked to see if that helps.

 

[cerberusiam]

Unless it is stuck in permanent regen doubtful that will help. the regen will use extra fuel and maybe that is what is happening.

 

[Jim W]

How are you calculating your fuel mileage, by hand or the over head LIE-O-Meter?

What was your fuel mileage before you notice the decrease.

How long has your fuel mileage been deteriorating! Just recently or over time.

Have you done an oil sample lately or at all?

I would do an oil sample to see if you have a higher than normal fuel dilution in the oil! This could be a due to an fuel injector leaking fuel into the oil!

This is just a guess on my part but your injectors are over 100,000 miles so, it could be one of them.

If my memory severs me right if you have less than 1% fuel dilution in 3 gallons of oil you are OK. Now if you are between 1% and 5% I would watch this over 5% you might have a leaky injector.

just something else to consider!