Pee Poor Mileage

[Strokin' 6.0]

I was at my local indy mech yesterday, picking up our BMW, and I found out that they also work on PSDs...the lead mech has an F250 6.0 that's lifted with 38's....he says he gets 19MPG with an SCT programmer on it.

Anyway, I was talking with them about the crappy mileage I get and the OASIS report, where the original owner took it in because the mileage dropped, right after the engine and turbo were replaced (43,956 and 54,814 miles, respectively)...the mechs told me that they would bet the farm that the engine and turbo sent a bunch of crap down to the cat and muffler, clogging both of them up, causing poor mileage.

Does this sound kosher to everyone? The previous owner reported getting 17MPG, prior to it tanking.

I just find it hard to believe that a clogged cat and muffler wouldn't exhibit other symptoms, besides a loss in MPG. If this is true, I know what I'm doing next.

Thanks for the replies.

[superstinker]

Originally Posted by Strokin' 6.0

I was at my local indy mech yesterday, picking up our BMW, and I found out that they also work on PSDs...the lead mech has an F250 6.0 that's lifted with 38's....he says he gets 19MPG with an SCT programmer on it.

Anyway, I was talking with them about the crappy mileage I get and the OASIS report, where the original owner took it in because the mileage dropped, right after the engine and turbo were replaced (43,956 and 54,814 miles, respectively)...the mechs told me that they would bet the farm that the engine and turbo sent a bunch of crap down to the cat and muffler, clogging both of them up, causing poor mileage.

Does this sound kosher to everyone? The previous owner reported getting 17MPG, prior to it tanking.

I just find it hard to believe that a clogged cat and muffler wouldn't exhibit other symptoms, besides a loss in MPG. If this is true, I know what I'm doing next.

Thanks for the replies.

How poor mpg are we talking about?

[Strokin' 6.0]

11.2 - 11.4 on the highway. Very rarely will it get into the 12 MPG range. Once, a long time ago, I had it at 16.2 (I was on totally flat ground), but then it went steadily down. I keep it at 2000 RPM. I tow often enough with it, keep the turbo exercised and change my fluids and filters changed regularly (5,000 for oil, 10,000 for fuel and 24,000 for tranny external).

I know winter fuel has something to do with it, but this is excessively crappy.

[superstinker]

Yes I must say that is pretty crappy mileage. I would get 16 on the highway on my 04 and in the winter 14 to 15. Does it seem like it is starving for power? Is there good flow from the exhaust?

[Strokin' 6.0]

Doesn't seem like it's starved at all. If I hit the go pedal, I get the normal VGT lag, then it boogies. I've never put my hand over the exhaust, but I would think that if it had blockage, I'd hear/feel it, no?

[superstinker]

maybe you might have to put it on the scanner you might have a soft code for a problem as this does not make the cel come on

[sho91mtx]

Maybe they flashed the computer? I know some strategies made the fuel mileage go down. Off topic, I'm assuming you're stationed at Goodfellow? I went there for fire school, place is a hole!!! I'm sorry

[Strokin' 6.0]

Originally Posted by sho91mtx

Maybe they flashed the computer? I know some strategies made the fuel mileage go down. Off topic, I'm assuming you're stationed at Goodfellow? I went there for fire school, place is a hole!!! I'm sorry

Yeah, I work at Goodfellow and you're right, it's a hole. I was an Intel Instructor, but now I work in the S3 and I'm ready to put a bullet in my head.

I had the FICM replaced recently, under warranty, and Kenner Diesel reflashed it with the latest strategy, but it was getting lousy mileage before that.

[lubbockguy1979]

Are you going by the digital read out? (Not accurate often called the lie-o-meter) How many milea per tank? Hand calculated is the only way and while ur at it fill the tank to a line of sight. That way you have some basis to get a repeatable result. For the mechanic getting 19mpg I'd say he is probably either bad at math or lying. Another item to mention. Idling will kill your mpgs quickly. Now for the reduced mpgs reported by the old owner.. It is very common for the 6.0 trucks to get reflashed thru out the service visits. Most complain that there is less power as well as reduced mpg. I'd assume the cat would have to be plugged up to reduce mpgs and also severly reduce power at the same time.

[lubbockguy1979]

Btw I graduated from wall. (2mi out side of s.a.) That town is a lot better then when I lived ther 10yrs ago. It has grown a lot. It almost looks livable. To the topic after you have made sure your mpgs are hand calculated, no idling and filled to a point of sight (ulsd is very foamy I can usually squeeze 8-10 gallons after the first time the nozzel clicks off.) These will help you to get a base line. If you still have sub 12mpg in town and don't drive like a maniac then I would get it scanned for any obvious codes (use a auto enginuity or ids or a good scanner that can do all the different modes not a cheapie autozone or tuner code reader), check ficm voltage and change the fuel filter to oem (racor/ international/ motorcraft) unless that is what you run already. Might also check fuel psi. Just a few places to start.

[Strokin' 6.0]

Originally Posted by lubbockguy1979

...To the topic after you have made sure your mpgs are hand calculated, no idling and filled to a point of sight (ulsd is very foamy I can usually squeeze 8-10 gallons after the first time the nozzel clicks off.) These will help you to get a base line. If you still have sub 12mpg in town and don't drive like a maniac then I would get it scanned for any obvious codes (use a auto enginuity or ids or a good scanner that can do all the different modes not a cheapie autozone or tuner code reader), check ficm voltage and change the fuel filter to oem (racor/ international/ motorcraft) unless that is what you run already. Might also check fuel psi. Just a few places to start.

MPGs are hand-calculated...364 miles with 32.15 gallons on last refill (11.3 MPG). Never idle the truck, don't drive like a maniac, FICM recently replaced, OEM Motorcraft filters. No codes, according to Kenner's. Fuel pump replaced by Ford under warranty. Haven't checked fuel psi.

Do you buy the clogged cat/muffler scenario, lubbock?

[teamroper60]

If the cat or muffler were clogged up, there would be massive backpressure in the exhaust system which would cause poor performance all the way around, not just fuel mileage. Thus, it would not "boogie" under any circumstances, so I doubt that is your problem.

One thing I would check is your IC boots.. A pin hole or split in one which could negatively affect fuel mileage. Driving easy, you would likely never notice the loss of boost (I didn't unless I was climbing a hill and I was towing a 14K 5er).. Mine was on the underside of the boot that connects the turbo to the hot side tube. Once I changed the boot, my turbo lag decreased, the mileage went up a couple of miles to the gallon and performance climbing a hill improved greatly..

[Strokin' 6.0]

Originally Posted by teamroper60

If the cat or muffler were clogged up, there would be massive backpressure in the exhaust system which would cause poor performance all the way around, not just fuel mileage. Thus, it would not "boogie" under any circumstances, so I doubt that is your problem.

One thing I would check is your IC boots.. A pin hole or split in one which could negatively affect fuel mileage. Driving easy, you would likely never notice the loss of boost (I didn't unless I was climbing a hill and I was towing a 14K 5er).. Mine was on the underside of the boot that connects the turbo to the hot side tube. Once I changed the boot, my turbo lag decreased, the mileage went up a couple of miles to the gallon and performance climbing a hill improved greatly..

I'll check them this weekend. The one thing I do notice, and I don't know if this is normal for a PSD, is that I can hear the turbo while I'm driving down the road. Parts of US Hwy 67 are flat and cruising at 60MPH, it sounds like the turbo is constantly spooling....not super loud, but I hear it. If I let off the go pedal, the turbo noise decreases. Since I'm still relatively new with the PSD I don't know if it should sound like this....my '05 CTD Ram didn't...then again, it wasn't a VGT either.

[69cj]

All though mine is an 05, I can't hear the turbo on flat land at all. That could possibly be an indication of a cac leak.

[Strokin' 6.0]

Crap......