Well I finally went down to my next unit at FT Hood TX.
Took a little over 18 hours of driving time, went smooth for the most part of the trip. I personally enjoyed the 1k mile tirp but man...this one burned me.

I couldnt help but notice that I filled up quite often, used 91 gallons for a 1119 mile trip. Thats 12 MPG!!! Truck used to get 20's, then went down to high teens, now its getting 12MPG????

Diesel kleen was added to every tank prior to filling up each time so I mixed it in good.

AE shows noting but EBPV fault, as its disconnected.

Cannot find any sort of leaks, fluid or boost wise.

Cruising at 63MPH, 1800-1900 RPM she held 5 lbs +/- 2 lbs. Roads were mostly flat and long, DP on 80E. Truck felt like she was all there, didnt notice any lose of power, in 6th gear she would move pretty good when I she had to, but noticed the fuel gauge moved to quick, overall

Things done before trip.
Fuel filter changed
oil/oil filter rotella Syn
oil pan changed (not the so great way, ha but still works)

My 6637 is a LITTLE dirty, and I really cant see how it being dirty as it is slaming my MPG down like it is. But maybe someone in the (Bell County, FT Hood, Killeen) area knows were to get a new one locally ill change it out? Im inprocessing so they wont let us go to far from the 21st replacment.

Maybe im missing something so simple...ill kick myself for not noticing???
But 12MPG from my truck is horrrrrrrrible compared to what it got just a week prior. I drove it like i was trying to save fuel but instead i got 12mpg...still cant belive it.

Ill make a seperate thread for the oil pan change with some good pic's went i ge the time. But right now im alot concerned about my MPG. Ive got my AE with me so if someone could tell me how to use that if its needed i might be able to find it.

Maybe im missing somthing????

 

oh-rye-lees might have one in stock. if not they can definitely get it fast. i would change the filter and double check all the boots. make sure they are nice and tight.

 

Could it be a combination of the fuel quality or winter blend or both?

 

I know you said you dont think you have any boost leaks, but what do your up pipes look like? Good and soot covered? (To see them, you need to crawl under your truck, and shine a flashlight on them. At a consistant 63mph, I would expect 16 out of my 9k # truck. 70 for me is 15mpg, and 60 is 17mpg. I see you also have 35" mud tires. Did you have them aswell when you got 20mpgs?

 

Welcome to Texas. I'd just order the filter from Fleetfilter dot com. They're located in Brenham, so you'll have the filter delivered in one or two days at a better price.

Mike asked a good question about the tires. If you've changed size, your odometer / speedometer is off so you won't get accurate readings.

 

12.296 mpg uncorrected makes 13.403 corrected for 35's (9% change). Still a big drop if you saw high teens or 20's. Check the uppies. May be time for bellowed uppipes. 5lbs boost sounds right, but may want to check IC boots too.

 

OK, I'll admit I'm too lazy to do the math, but a lift, the additional weight for the move, winter fuel and a headwind could combine for another 3 maybe 4 mpg hit. Uppipes does sound like a good place to check.

 

I had the same problem with a consistant drop from 20's to 16's b4 I happened to read a post on the FTE forum and someone mentioned to check the SS line from my right exhaust manifold and the sensor it connects to at the top center of the engine. It was plugged with soot. Once I opened up the line with a weed eater string and a drill and a drill bit into the sensor(be very careful not to go into the diaphram) I twisted the drill by hand. I had almost overnite an improvement back into the 20's and am loving it.
I wish I could recall th eproper names. Take a look into that.

 

You cleaned the EBP tube and sensor like this Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

 

Ok...finaly got internet in my room.

EBP tube was cleaned and new sensor was put in. Prior to the cleaning/replacement the sensor itself was glogged beyond cleaning.

Didnt change tires, 35s with 45lbs in the front and 43 in the rears

upipes are very clean, just lit rust. i checked them good when i replaced the UVC's and installed the cakle cure kit.

Boots are old but still in good shape, i planned on replacing em but never got around to ordering new ones.

from another thread i posted on about oil temp reading way high, i remember running AE on a few good runs of the truck and i noticed the bar for oil temp was far in the yellow almost red, could this also contribute to the drop?

Im sure fuel has a huge play in it, i do understand the odometer cuz i dont have it corrected, but from my numbers last year, it's dropped way to much for me not to try and do somthing about it. I'de be happy with 17mpg at this point, I ran 600miles round trip to IN and back a week and a half ago and got that.

Would alot of blow by cause a rapid drop in MPG? I've noticed a little more puff, but I figured it was cuz of the oil change.

I got bellowed pipes sitting in the truck, dont have time right now to switch em

Ever since i got the DP, shes been having some major changes. Ive got the ole TS chip i think Ill switch back to it to see if anything improves.

So far loving Texas wheather!

Thanks for the replies guys.

 

I saw better mileage switching from the TS to the DP. Alot of blowby is not a good thing and i would think would result in a drop in fuel mileage. Just my $.02. The winter fuel would come into play, but in VA we haven't switched over yet, so i can't imagine Texas switchin already. Are you running the same oil that you ran when u clocked 20's?

 

yep same oil, since i bought her. rotella syn, fleetgaurd/motorcraft filter

I did use different brand fuel filter....bought from napa cuz when i looked at my old one it was BAD from the B100 the summer before. I think WIX??? but it was the single element and was all one peice. Somthing i will check also this 4 day weekend.

as for winterblend, it is to warm yet in TX for it i belive.

Ill check blow by again also

busy busy week

 

Yep, just flip over the oil fill cap and lay it on top of the fill tube. It'll vibrate off, but you'll be able to tell the difference in falling off and getting blown off. Let us know what you find.

 

that is a big mpg difference. don't think Texas has switched to winter blend yet. it was in mid 90's this weekend. i'm right down the road in Temple if ya need me to bring you something.

 

I am intrigued by the high oil temp, let me just say that it falls in two categories and here is my thoughts.....First high oil temp because the sensor is bad, could the PCM be changing injection timing based on bad oil temp reading causing decrease in fuel mileage.....second you really have that high of an oil temp which is indicative of another more serious proplem that needs to be addressed (I would guess a friction problem / Oil cooler problem / ???)

One other question for you....what cps are you running in your truck, I tried the blue cps with the DP (my other cps crapped) my mileage went from 17.5 to 14 I then replaced with a black one and everything is back to normal.