Gas Mileage

[Michael Gabbay]

Over the past several fill ups, I've noticed that my gas mileage is off by a couple of mpg in my Honda Pilot. I've been driving the same commute to work and using the same type of gas. The only thing that has changed is I took it into the dealer a few weeks ago to get the 13K mile service (oil change, tire rotation, filters etc.).

I normally average 18 mpg, now I'm getting around 16mpg. For all of the grease monkeys, any ideas for such a dramatic decrease in mpg?

Mike

[John Miliunas]

Mike, I'm far from a "certified" grease monkey but, I can't help but wonder if while they were in there swapping stuff out, if a vacuum hose didn't inadvertenly get disconnected?

[Mark Cothren]

I'd double check air pressure in tires, visually inspect for any loose vacuum lines as John has suggested, and also inspect your air filter/cleaner to make sure they changed it and it isn't clogged up.

Are you noticing any change in performance (loss of power, etc)?

I took a vehicle in to a dealer for some work and had them do a tune up while they had it in there. I was billed for a full tune up (including plugs and wires) and less than a week later when I had a miss in the motor I realized that I still had the same plug wires - not the new ones I paid for...

[John Miliunas]

I took a vehicle in to a dealer for some work and had them do a tune up while they had it in there. I was billed for a full tune up (including plugs and wires) and less than a week later when I had a miss in the motor I realized that I still had the same plug wires - not the new ones I paid for...

Eeeeeek! And on today's motors, them thar wires are some of the most expensive components on the tune-up!!! Hope you got it resolved!!!!

[Dan Larson]

Have you been having colder than usual weather lately? Outdoor temp can influence mpg significantly. Granted you have a more moderate climate than we have here in WI, but my average mpg drops by as much as 15% during the dead of winter.

Dan

[Bob Johnson2]

I live a bit farther north, but I get a couple mpg less in the winter, don't really know why. I know the gas formula is different this time of year, but that's just a guess.

[Dan Larson]

I live a bit farther north, but I get a couple mpg less in the winter, don't really know why. I know the gas formula is different this time of year, but that's just a guess.

I think it has to do with engines needing to run on a precise fuel:air ratio. Cold air is more dense, so more fuel is needed to maintain the correct ratio. Side benefit of this is that the engine makes more power on a cold day.

[John Miliunas]

Have you been having colder than usual weather lately? Outdoor temp can influence mpg significantly. Granted you have a more moderate climate than we have here in WI, but my average mpg drops by as much as 15% during the dead of winter.

Dan

Ditto! Don't that just suck??? Doesn't really seem to improve significantly until the temps start to top over 30°, either! Oh well...At least it's not as bad as it was last month!!!

[Steve Ash]

I don't have anything to add to the reason you may be expieriencing a loss to your gas mileage....I was surprised that you aren't getting more than 18. I get 18 m.p.g. with my 1969 Chevelle ....as long as I just cruise that is.

[Joe Pelonio]

While not a mechanic by trade I've been doing most of my own work on cars since I was 14 (1966) especially on my '72 El Camino, so here's my 2 cents.

I don't know if it's every state, but here and many others are selling only oxygenated fuel during the winter. That typically reduces you mileage from 2-10% depending on the car. It can also cause driveability issues. The reason they do it is to reduce winter emissions when it takes longer for cars to warm up to normal operating conditions and when they are at peak efficiency.
If the pumps are labeled that it's oxygenated you really cannot do anything about it. If it doesn't go back up in the spring when the normal fuel returns then it's likely something else. Some of the other causes besides those already mentioned are: Leaking fuel injectors, carboned up throttle body, dragging brakes, misaligned wheels, worn wheel bearings,
transmission slippage, engine running too cold, even faulty speedometer.
Most of these condtions would not set a check engine light. Also, if you are using the defroster a lot it's like running the A/C since it kicks on to dehumidify.

[Jim Becker]

Colder temps, different fuel formulas, etc., combined with defroster (A/C!) use will often lower mileage during the winter months. Late spring and early fall are usually the best in my experience...

[Dan Larson]

Oh well...At least it's not as bad as it was last month!!!

Yeah, we've gotten off pretty easy this month. If it weren't so dang dark outside all of the time , you might be able to convince me that it's already March.

[Michael Gabbay]

I'll check the vacuum hoses and air filter. I'm sure the air filter is clean since I checked it before I took it in so even if they did not replace it I should be ok.

Tire pressure looks to be good.

I rarely use the AC for my defroster. For the last tank I did let the car idle and warm up since the weather was not too bad.

My commute is about 5 miles with a mix of city and about 2 miles highway. Normally highway only I get about 22 - 23 mpg. And I don't have any dead bodies in the back. They are up front!

Thanks Guys!

[Anthony Anderson]

Did you make sure they used the fuel efficient oil filter? If not, that can account for the 2-3 mpg fuel loss. HTH, Bill

[Michael Gabbay]

Anthony - I've never heard of a fuel efficient oil filter.