2017 f350 normally pulling trailer get around 8-9mpg. The fuel consumption went way down to .5 not 5 .5 mpg last 20-30 miles. I’m hoping someone is going to say Regen mode. I actually checked for a fuel leak. The miles to go light came on at 50 miles to go I went about 6 miles dropped to 35 to go. After that I was clocking it at 2 Mile loss at every mile traveled. We are taking level 40-50 mph speed. Barely made it fuel station. Drive last 8 miles to destination and lost 16 miles in the to go range. So I reset the trip odometer after fuel and found the .5 mpg. The fuel gauge looked like vacuum gauge dropping significantly too when almost out. I’ve made this exact trip for years and always had 100-150 miles to go. I’ve never had to fuel up.
the other part to this is it only has 22k miles. My ac went out andthe dealer replace it. Got it back and made this trip. Noticed a significant turbo noise that was never there. Almost like a hose was left off the intake. I don’t see anything wrong from a quick look on the side of the road. Any ideas and do you think they are related? At this fuel rate it is going to cost me $4000 to go 380 miles back home. I’ll drive it around town unhooked tomorrow and see if it is still doing it. I’m hoping Regen mode. But the noise is also a problem. Only on high boost does it appear.
appreciate any help!

 

Just spit balling, possible boost leak??? Engine can’t build power without boost. Use more fuel and runs hotter with LESS power when less boost. Just an idea.

 

CaC pipe broke?

 

If you blew one of your intercooler pipes enough to cost you that kind of fuel, I’d also think you’d notice a huge drop in power. Aside from the noise, does it otherwise seem to run ok? I can’t imagine what would drop mpg to 0.5. That’s nuts. The check engine light isn’t on?

 

So it's not electrical false reading because you said you filled it up so it must have taken 2-4 gallons less than tank holds. One would think your pulling legs here as it would be draining out the tail pipe, smoking or providing some visual. $4K to go 380 miles, 1/2 a mile per gallon, this is a gag.

 

Awesome. Thanks for the quick replies. Fired off the question while setting up the 5 Th wheel and a couple other must do’s.,
so power seemed fine. I came down 395 from northern nevada. Snow and ice but relatively light compared to previous trips in Jan and feb. so the air filter was dirty and had 9k miles on it. Ran into a lot of road base and crap blowing from the side of the road. Might have helped dirty it up. Especially through the desert. Had several knuckle heads decided to blast the Highway with their antics. But I’m thinking the main thing had to be Regen. I’ve never seen a message or heard a beep or anything. No check engine light. I don’t know when it goes into Regen.
i went to the parts store got a new air filter. No trailer. Sound is fine but no 16k pound load either... didn’t check it before the new filter without the trailer. too much traffic..
So the miles to go above the fuel gauge is still dropping faster than the odometer climbs. I would think it would be about a 1:1
it isn’t ridiculous like before. Much more reasonable. Hence my thinking it was related to Regen.
the first odometer I reset. Shows about 17 mpg on 10 mile loop. 2nd one is combined trailer towing etc around 9.9.
3 red is the fuel economy average with the bar. that one showed 10.8
so the miles to go above the fuel gauge is more dropping one mile for every .7-.8 miles driven. At least it is not ridiculous like before.
I’ll drive more around town in the next two weeks. will see how it all pans out. I guess I can do some research on the Regen process. I would think it wouldn’t go when under a quarter tank? Not would I believe it would be so ridiculous on the fuel consumption. Perhaps there is still an issue. I’ll keep ya updated as I noodle this out more. Headed back at the end of the month so might hit Regen again while towing home. At least I’m not going to have a massive fuel bill. Dang diesel is like gold in California. $1.40 more per gallon than at home.
thanks again for all the replies. this took a while to write as I’m getting implored to set up the Apple TV, Alexa, space shuttle communications, WiFi for the block, etc...
but wanted to get you guys an update as I appreciate the quick replies and concern!
Cheers. Off to beer thirty!!!

 

I agree about the .5 mpg. I don’t know what the he’ll was going on. I looked for a fuel leak. I still don’t know why I barely made it to the gas station. I know it is not doing it now. No smoke no check engine light ran fine. 210 degree on oil temp. I am at a loss for explanation. I’m hoping it is gone for good. But it wasn’ta joke or gag. Unless an electrical gremlin took residence, Regen is an issue? Idk?

 

So for clarification. I didn’t fill it up. The pump stopped at $100. My credit card got a fraud alert. Texted the number to clear it and they wanted a phone call. So rather than tie up the pumps, I left with about 1/2 tank.

 

Thought I'd provide an update. After 4 trips to 2 different dealers. All telling me everything is ok. Re flashed computers and updated programming etc. Last time the emission light came on. Finally, something to prove there is an issue. Other than me telling them it is in limp mode giving me 60% horsepower when towing. Months of dealing with this... 2nd time in had them add the DPF screen to tell me how full my Filter is. Towed over 4th of July and for 100 miles it was not regen'ing at all. Temps were high to say the least considering I had to pull grades in 3rd-4th gears due to it running like crap. Grades I normally pull 25 mph faster in 5th and 6th. Filter said 99% full. Took lots of pictures to show the next service advisor. Looked for independent dealers to provide a manual regen and although some could do it, none could do it for at least 6 weeks. Well, that works great when your at a campground and have to leave in a week.... Other than ForScan couldn't find anything that would manual regen. So, I provided great care of the environment and drove around for an hour in the hills while patting my head, rubbing my tummy, standing on one foot. Parking on the side of the road with the hood up and parking break on at 2,000 rpms; all while holding my breath. Well, another 40 miles or so and headed back to the campground it started to regen. Hurray. You'd think I won the lottery... Now, drive another 1/2 hour out of my way to get the thing down to 25%. Great should make it home now...
Another trip to the dealer and again. Needed a "computer update". I'm starting to think they are just clearing codes and crossing fingers. They drove it and said all was well. Picked it up. When I picked it up I asked the service advisor to set me up an appointment in one month as I was going to tow at the end of the month and I'll bring it back for the same issue. He gave me a deer in the headlights look. Said they fixed it. I said I've heard the computer reflash fixed it too many times now. I'm a realist. Probably a sensor acting up when hot/cold OR something? Well I made it 1 whole block before the emission light came back on. Have no idea if power issue was back as I was in the city. Took it right back and gave him the keys. I was very nice as he didn't give me too much static about the appointment in a month. Couple hours later I get the call they are going to replace the EGR valve. Its on order. Hopefully we are not at the lets throw parts at it point. To say this is frustrating is an understatement. At 25k miles now this emission crap is getting old... But, at least they are going to start replacing parts. Good thing I have the 100k mile extended warranty. Or maybe not. I am starting to think the best course of action is have some degenerate steal my exhaust..... Wouldn't mind getting over 7mpg towing... And I tow at 55-60 mph. Not like I'm some cowboy running 90...
Seems in the beginning it was regin'ing like a flood. Now it is hardly at all...Now that I have a gauge I can at least see when it is full and needs a regen. Unfortunately, I was told if I get something to manually regen I void the warranty. Well, if thats the case, I'll just remove the garbage.

 

BTW: When they reset the computer it runs normal. No loss of boost. Fuel mileage has a slight improvement. But, interestingly; when it goes to limp mode the TURBO only goes to low side of R instead of high side of O. Have no idea how much loss of boost that is; but, feels like someone is pulling it backwards.

 

I havent read all the post but

summer fuel blend?
Air pressure in tires?
Different tires?
Head winds?