02 Camry gas mileage suddenly has detetiroated! Help!

[Ducaire]

For the longest time, I've always averaged about 37 mpg out of my 02 Camry, give or take a couple of miles (depending on whether I did a little bit of stop & start driving in town or not). Well, last time I filled up with gas, I noticed I only averaged about 34 mpg. I thought, "no big deal, maybe I'm not letting it coast to a stop like I've been doing".
So, I tried again, and this time I really took it easy, and only came up with 31 mpg! Could it be the store is putting ethanol in their gas (they say you won't get as good a mileage) or heating their gas up??

-It's NOT my driving, I only do 55 mph, I hardly went into town and I haven't been "putting the petal to the metal" so to speak.

-I checked the air in my tires, they had about 36 psi in them

-My engine runs and sounds just fine, so I don't think it's a filter somewhere (although I could be dead wrong) I don't notice that it's lost any horsepower because of a dirty filter (although you may not be able to tell at first).

What gives? Thanks.

[DFBonnett]

Are you due for a tune-up? Was the weather appreciably colder during the last mileage cycle?

[2000izusu]

i know during winter my mileage drops due to winter blend gas and due to the fact that vehicle takes a while to warm up. causing the 02 sensors not to take over fuel trim until it is fully warmed up.

[Mike Gerber]

Originally Posted by 2000izusu

i know during winter my mileage drops due to winter blend gas and due to the fact that vehicle takes a while to warm up. causing the 02 sensors not to take over fuel trim until it is fully warmed up.

I have to agree. In the colder months my fuel mileage drops around 10%. That is not only because of the Winter blended fuels, but also the longer warmup times the engine experiences. In the real cold temperatures, like around the zero degree mark (we will be experiencing those temperatures this weekend in the Chicago area) my mileage may drop by as much as 25%.

Mike

[RIP]

For a bit I was getting discounted gas from a Sam's Club store. The discount was great untill I noticed I was getting 2 to 3 less mpg than I was use to. I went back to my original source and the mileage returned. Try another gas station.

If weather isn't the issue and I would expect in Georgia it's not, there are many possibilities. Dragging brakes for one and they don't have to drag much. Drive it around a bit and feel the wheel/hub for temperature differences. Might have to carefully touch the rotors. Another could be an engine management issue. You'll have to connect a scanner, probably one with a real time function to pinpoint the problem. Short of that, O2 sensors are known to deteriorate before they fail. This will effect air/fuel mixtures and your mileage. If your car has over 80K miles, you might consider changing the upstream sensor. They can be pricey though. Another is suspension problems. Anything that effects wheel alighnment can effect your mileage. Look for abnormal tire wear.

Are you seeing any symptoms at all? Something like rough running now and then, a check engine light, rough or slow shifting, a heavy gas smell, or pulling to one side or another? Are you keeping up with scheduled maintenance?

[Ducaire]

I've been letting it warm up on those cold mornings for about a minute or so (it doesn't take that long to warm up unlike my truck), but I didn't think that would hurt the mileage that much. But if the cold can have something to do with it, I'll bet anything that's what it is. I may live in south Georgia, but we've been having some 30 degree F. mornings here lately.

I just made a nice OTR trip to Callahan Florida, and my mileage significantly improved.

[xfeejayx]

Originally Posted by Ducaire

I may live in south Georgia, but we've been having some 30 degree F. mornings here lately.

Mike will probably agree that 30 degree would almost be a heat wave at this point in Chicago.

Yes even that minute or two warming up will make a difference. And even if you are only letting it sit for a minute, you're car is still taking longer to warm up even when you are driving. Winter gas also makes a difference, and colder weather also makes a difference for reasons other than warm up time.

Getting 37 mpg consistently on a camry is (for most people/conditions) pretty hard to do, and even the smallest changes will drop your mpg really quick.

I think you're fine for now as long as there are no trouble codes.

[Mike Gerber]

"Mike will probably agree that 30 degree would almost be a heat wave at this point in Chicago."

Yeah, that -6 yesterday morning was no day at the beach. I didn't go out until the temperature warmed up to a balmy +2.

Mike

[jdmccright]

With engine management computers and fuel injection, vehicles no longer need to be "warmed up" prior to driving away. All you need to do is start the car, put it in gear and drive away...albeit a little slower and gentler. The car warms up best and fastest when being driven, not idling in your garage or driveway. This way, you aren't burning gas going nowhere...causing your lower mileage. If you don't like a cold car in the morning, well, that may be a personal preference that you'll have to pay for. Instead of blowing cold air on me, I just turn off the heater fan until the temp gauge starts to move.

The ethanol blended fuels do reduce mileage due to their lower energy density, and cold temps will cause an engine to run richer longer until the engine sensors detect normal operating temps.

[Ducaire]

Thanks everyone for your replies.

RIP: It does pull to one side on occasions, but not all the time. It actually pulls to the left at 55 mph, but at 65, it'll run straight as an arrow. (It's pulled though since I've had it, and it got good gas mileage then until a couple of weeks ago). I guess it is the colder weather or perhaps the winter-blend fuel.

[Brian R.]

See new thread on idling vs driving cold.

http://www.automotiveforums.com/vbul...d.php?t=884529