Fellas,
Since winter hit it seems like I am getting HORRIBLE fuel mileage, like 10-13 mpg city driving...lots of short stops. Normally I get 16-18 in town and can pinch 20 out on the hwy.

Is this due to winter fuel? Is anyone else experiencing this? I have filled up at a couple different places and it seems to stay the same. Also, I am noticing 178-180 ECTs. I assume I have a stuck t-stat, would this play a roll in MPG?

Is there any thing to trouble shoot on this? Refer to my sig for truck info.

Thanks

 

Winter diesel alone will account for 10 to 20% drop in fuel economy.

In your case, I suspect a mild limp mode if it detects a non-working EGR. Is your EGR valve plugged in?

 

EGR is plugged in and cooler has been blocked off for about a 1.5 yrs now.

 

Your ECT is low.

Yes, stuck thermo is suspected.

Have you tried to unjam it?

I unjammed mine without a replacement by some spirited driving / heat / cool cycles with a bubba shield.

You may just elect to replace it to save yourself the trouble.

Also try a bubba shield.

 

Will the low ECTs affect MPG significantly? I understand low operating temps= poor efficiency but wouldn't think it would hit MPG that much?

 

Winter fuel.

Plus when it's COLD:
* lower tire pressure
* longer idle times when warming up in the morning

Yep, it's not surprising.

 

If you wack 10-20% from fuel alone.

Then... is there a software routine that injects more fuel while it is warming up (to heat it up faster)?

If the thermo is stuck open... does that mean it never heats up and keeps doing the extra fueling?

Need a Ford guru to talk to us... the software is proprietary.

 

I have one of my obd guages set to watch instant fuel economy right now (kind of useless normally, i know). There is a definite difference in fuel usage below 150 degrees. I'm talking getting 4mpgs with engine rpms at 1700 rpm going 45mph on the flat difference. As soon as temps rise mpgs jump back to normal. Oddly enough no noticeable difference in power.

 

Yep, I didn't have specifics like Kert, but generally I see the same thing
on my ODBII as well.
And I'm pretty sure I don't have winter fuel in Orlando, FL.

 

cooler air can reduce mileage also. my milage always goes down in winter and increases in summer.

 

You are getting the same numbers I am. I am just assuming it is from the extreme cold we are having here in UT. Single digits at night, low 20's in the day. I will hit 180-183 on the highway, at a stop light it will drop to 178-180.

My fuel milage drops a lot in the winter. I am getting about 11.6 on 50/50 highway/city driving.

 

You guys are great, thanks for all the info. Sounds like this is just typical then. I'll be replacing that T-stat soon.

 

Don't forget.. in cold weather, you are bleeding heat from the heater, and also generating electricity to run the fan, seat heaters and other energy consuming devices.

I am more and more thinking there is a "rich burn" deal

 

I am getting a drop in mpg's as well do to the winter temps and fuel. I can live with it. I always tell people that if you think our 6.0 gets bad mpg's in the winter they should have the experience of owning a V-10 or a 5.4 in a Superduty!!! I have had both gas engines and my 6.0 is still on top all around for mileage.

 

It's the fuel and not the air temperature that's effecting everyone's fuel mileage; we go through this every year. Cooler/cold air is more dense than warm or hot air...thus it would expand more when the fuel lights off and create more power. That's the whole name of the game when folks are using NOS or Water/Meth injection on their rides...regardless on the fuel they're burning (gasser or diesel). When the turbo compresses the air it's hot, thus it's passed through the inter-cooler (after-cooler if your talking about a Caterpillar engine) to cool it back down.

As it's already been pointed out, not only does the fuel have a lower BTU because of the winter blends...but most of us idle our trucks a little longer than normal this time of year. Seriously, who wants to ride in an ice cold truck? Thus, that extra idling burns more fuel.