I have just shy of 25,000 miles on my 6.4. I added 37" Toyo's to it before the latest PCM recall. I had received 17.5 MPG going to Denver, CO. crusing at 75 MPH. Needless to say I was stoked with that mileage with 37" tires. Around town I was getting 12 - 14 MPG. I had the PCM recall done and my mileage did not get affected at all. Until recently! I had been noticing a steady drop in mileage and was hoping that it was a fluke. Just last Saturday I traveled to Cheyenne, Wy. to get some service work done to our Polaris Ranger. Going up and back I could not get over 8.8 MPG. Once I returned I EMailed my service advisor and stressed my concern to him as well. Got a call this morning and he had contacted FORD for their thought on the issue. He also stated to me that he would need my truck for 2 full days to dive into it and see what they could find. FORD had told him that they will need to check out items like the Fuel System and Injectors. I am guessing that they will check other things as well. I have not noticed any loss of power nor do I have black tail pipes they are quite clean. I did have an EGR valve replaced recently because it was stuck open. I am very happy with my Dealership for service. I am just wondering if anyone else has experienced issues like this. I would expect to see a drop in fuel mileage with the addition of the 37's but not this drastic! Let me know what you all think.

Thanks,
Jeff

 

I dont have an answer but I am tuning in to see what you find out. Mine has dropped significantly since the reflash. I have tried several different driving styles, speeds, loaded and empty and I have definitely lost mpg.

How many miles do you have on your fuel filters? Mine arent due yet but I am considering changing them just to see if it helps.

 

I am not a very smart man but changing your tire size is going to effect the LOM right?? Did you hand calculate your mileage?

I have gotten better(1 to 1.5 mpg) mileage since my reflash.

 

My fuel filters were replaced at 14,500 miles. Yes, the mileage was hand calculated also. Never above 9 MPG. I know that the tires will throw off the lie o meter so ,I wanted to hand calculate as well. It really seems like a large drop. As I was talking with my advisor he too was very shocked at the mileage reports. They sell lifted trucks with 35's and he told me that they have had no reports of that kind of mileage. SO I am really in the dark.

Any help would be appreciated!! Thanks again in advance.

Jeff

 

Definatley something wrong if you are getting 9mpg and under empty. I get 7 to 8 mpgs pulling 16,000lbs with my DRW 350 at 75 mph. Like I said I am not a smart man but I have heard lots of chatter regarding EGR failures. Would that reduce mileage? Don't know but trying to help.

 

I have had 8 - 9 when I have pulled all my toys granted I am at max GVW and I expect that kind of mileage just not with what I am doing now. Now that you have mentioned the failed EGR valve in this instance I too wonder. Although they did replace it. I guess the next 48 hours will tell the story. Thanks again!! Any input is worth an eye brow raised.

Jeff

 

Did you have to use anything more than a leveling kit to fit the 37's?

Be sure to post what the dealer does and the results you get. Thanks.

 

Would an open EGR valve give you better mileage? Would an EGR valve stuck half open give you better?

Maybe the opposite? The EGR valve could be an issue that is contributing to the fact that we all have such differences in MPG's.

I towed my TT about 200 miles yesterday, it weighs around 9000. I could only average 9.2 going interstate speeds, mostly around 70.

I generally get better numbers than most around this site. I also have more miles on my truck than most. I hope to hear what the OP's dealer does. It's exciting to see a dealer service dept. take enough concern to really dive into it.

 

Nothing else was done other than the 2" leveling Kit. It truly does look cool.

 

Got it dropped off this morning. I can't wait to see what they can find! I will report any findings as soon as they become available to me.

 

Quick update... As of 2:30 yesterday they called for approval to begin with replacing the Fuel Filters (S.A. advised that it was 3,000 miles early but wanted to begin there) also replacement of Air Filter of which the tech statd was dirty. I gave the approval for replacement. Also I asked about the injectors and he said it was on their to do list of checks. I will report back to you as more becomes available.

Jeff

 

Ok here is the latest... Picked up the truck and was told of the tests that were done. 34 DIESEL DIAGNOSIS 988 WS 24853 EEC TEST NO CODES. CHECK OASIS. PERFORM FRE CHECKS. PASS KOEO KOER. LATEST PCM PROGRAM. Replaced Fuel Filters, and Air Filter. Oil Change was also done (it was time for that).

I am going to Moab, Utah for some R&R and Trail/Rock Climbing with our Polaris Ranger. We are leaving Saturday and will return Wednesday. I told my Service Advisor that I would report back my findings as I will also report back on here. I did ask if nothing changes where do they go from there and his answer was a Fuel Injector Cleaning although with the low miles on my truck he did state that it was hard to justify. However he wants to find out what is going on.

Thanks for the input! Let me know what you all take of this.

Jeff

 

I'd rather drag my camper to Moab and hang with you than talk about MPG's and motor issues!

Seriously though, thanks for your info. This is probably the most productive inquiry to mileage issues that a dealer has agreed to tackle. Looking forward to your findings.

 

I have also seen WORSE fuel efficiency since my reflash. I did quite a bit of research, waited over 2 months after recieving the recall notice, and posted a thread here asking for feedback from guys who has had this done. All I got was positive feedback and most saying their MPG went up - so I got the reflash done.

Before the reflash, I was getting 14 mpg in the city, 19-20 mpg empty on the highway, and 10 mpg pulling my 9k+ RV. After the reflash, I get 13 mpg in the city, 17 mpg on the highway empty, and 8 mpg pulling my RV. I racked it up to Winter fuel since the reflash was done over the Winter, but I am still seeing these numbers.

The regen messages on the dash is a nice thing, but I prefer my old fuel efficiency.

 

king ranch, glad to hear that you have an interested and concerned dealer that wants to find the problem. I was all set to replace my fuel filters just to see if it helped but I am going to wait and see what results you see.