14mpg? Is this normal?

Is your tailpipe extremely sooty?

 

99, 2.7 ltr, 4x4, stock 31 x 10.5 BFG at's here. 21-22 city

 

Have you done any mods?

 

actually yes it is. Can you give me some insight please.

 

What have you done performance wise.

 

No real mods. The catalitic converter was replaced with a high flow because original cooked. Header added when stock manifold cracked multiple times. Original exhaust besides that. The air filter is a k/n. We had many of the same company trucks. All run the same mileage.

 

That can be an indication that your O2 sensor is starting to go bad and causing the truck to think it's running lean which means it pumps more fuel into the engine to correct the lean signal. Well all that fuel doesn't get burned and soots up the exhaust and causing poor mileage. Mine took several months before the CEL actually went off and confirmed my suspicion.

 

interesting. thanks, I'm almost at 100k miles. i will replace those asap and follow up

 

most cases it's the pre cat sensor. The post cat O2 rarely goes out.

 

Mines out....

 

I'm down 3-4 mpgs with the winter gas.

It really sucks.

 

The summer/winter blend change may be more radical in other states, but here in California, I'm noticing very little difference.

There are several factors in the winter that may affect MPG's; colder, denser air which creates more wind resistance, stiffer tires which may create more rolling resistance, and the big one, IMHO, much longer warmup times which cause you to run richer longer. Who knows, maybe a cold drivetrain is stiffer too (think of the manual transmission oil and gear oil viscosity before it warms up).

On super-cold mornings (for socal, that's 35°F), I have trouble getting over 21 on my trip to work whereas mid to high 21's come easy on warm mornings.

YMMV!

 

I guess that my Tacoma and I are spoiled; even when it's in the mid 30's outside, I rarely see a coolant temp below 60°F (she's garaged). Most mornings, the coolant temp is in the low 60's.
Also, I get to coast out of my neighborhood, so I don't even step on the gas until then, which means the coolant is over 100°F when I finally have to step on it.

 

I don't ever just let the truck sit and warm up. I drive like a great grandmother for the first 5 miles or so... and let it warm up that way.

Using the data on Fuelly.com there is a significant drop off once winter gas starts making its way to the pumps. Of course the other factors you mention also make a difference but I'm convinced it's the higher ethanol content more than anything.

 

I don't either, although I did when I was in Mammoth in January when it was 2°F.

 

So what do you usually average in the Summer if your all around average is 21.2?


On a side note. What engine temp does your ultragauge usually show? I get pretty good mileage with my v6 4x4 but my coolent temps are always 195-200 and I have noticed other people mention that theirs is 190-192. I am wondering if that little bit of difference makes a change in mileage.

 

Mine runs 199.4°F - 203.0°F most of the time. Not sure that the slight difference would impact mileage much, if at all.

Also to clarify an earlier point, when I spoke of much longer warmup times in the winter, I didn't mean sitting and letting it warm up. I meant that it takes longer to reach normal operating temperature. So if in the summer your engine is warmed up after 1 mile of driving and it takes 3 or 4 miles to warm it up in the winter, you will take an MPG hit compared to the summer scenario.

 

Agreed, warm it up while driving, idling is just a waste.

Same on winter gas, I'm stuck with E-10 year round. With E-10 my scangauge fuel adjustment pretty much stays the same winter/summer. If winter blend was much of a factor I would see my fuel adjustment change from say the current 8% to 9-10% if it made a difference but I don't see it. If I can find E-0 my fuel adjustment goes to 2-3% and I get about 6% better mpg immediately.

Poor mpg in winter has more to do with many things besides winter blend. Idling to warm up, drop in tire pressure if you don't maintain pressure, higher rolling resistance of cold tires, drag from snow and spinning tires on ice, lower engine temps while you run your defrost full blast never getting to full temp, thick oil and gear lube, more electrical loads including lights on morning and night with less sunlight, more aerodynamic drag moving through cold dense air.

 

Just a 'FWIW' to back up my comments regarding crappy mileage when your engine is cold.

Every day I mostly roll out of my neighborhood on the way to work, because it's mostly downhill, although I do have to hit the gas a few times. My engine almost always starts out at 60°F because my truck is in my cozy garage and by the time I leave my neighborhood it is roughly 110°F, 0.5 miles later. The Ultragauge typically shows that my short trip MPG at that point is between 10 and 11.

Today I made the exact same trip, driving the exact same way, about 15 minutes after I got home, so the engine was warm. When I left my neighborhood the Ultragauge short trip MPG was 21.

So, if my mileage is half of what it could be with a 60°F engine, imagine what it is with seriously low engine starting temperatures, in a really cold climate, especially without a garage.