2005 Accord - Sudden significant decline in miles/gal

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Greetings,
My 2005 Accord EX (2.4L) did average of 28 miles per gallon for two years (since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean absolutely nothing has changed in my driving habbits.
Then, sometime in begining of December 2006, all of a sudden I noticed a decline of about 20% in my fuel consumption...from average 28 to average 22.
Any one experienced this before? Any idea what could it be?
Thanks.
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Check items listed at http://home.earthlink.net/~honda.lioness/id11.html .
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and turn off the HTML and limit line length to <80 characters. (per UseNet convention)
--
Jim Yanik
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This coming from a guy who should be legally required to sign "idiot" after his name.
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Thanks for the link.
Is it possible that indeed something went caput, such as a valve, or something? I mean, tire pressure or things like that cannot cause a 20% decrease overnight. The car is still under warranty.

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My first suspicions would be (1) unusual cold, which can reduce efficiency a lot, like 10% lower fuel mileage; (2) ethanol or whatever loaded gasoline, required in some parts of the country; and (3) tire pressure drop; tire pressure can change radically within a couple of weeks and will easily reduce mileage by 5-10%. One should check the pressure every two weeks.
How many miles are on this car? Are you following the maintenance schedule for plugs, wires, and other ignition parts? Admittedly it's a very young car by years...
Yes it's possible something went kaput, but I'd expect a check engine light for the "kaput" item on such a recent model. E.g. if the oxygen sensor was defective, you should get a "code" indicating it's failing, and this would first be indicated by the check engine light.

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in winter months,gas suppliers change their mix of volatiles in the gasoline,add up to 10% ethanol for absorbing water,and all that can affect mileage. Tire pressure does make a big difference,too.I've got a slow-leaking right rear tire,and when it drops 5 lbs,the mileage drops noticeably.
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Jim Yanik
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The car has 27K miles on it.
I checked tire pressure - it is right where it suppose to be.
The reason why I think it's not cold weather and/or a change in fuel "ingredients" is that as I said, I have the car since November 2004 and I drove it since then during two winters, two summers, exact same roads and driving conditions....I mean literally nothing has changed. Also, this behavior started as I mentioned in the beginning of December and we had an unusual mild December here in New England, so I don't think it is weather related (even if it was unusually cold, I went through two previous very cold winters).
Is it possible that something is partially not functioning (like a semi-blocked valve or filter) in a way that it will not trigger the check-engine light?
I think I'm gonna have to take it to service...hoping they find something.
Thanks guys.
face="Times New Roman">...<BR>&gt;&gt;&gt; Check items listed at<BR>&gt;&gt;&gt; </FONT><A href="http://home.earthlink.net/~honda.lioness/id11.html "><FONT face="Times New Roman">http://home.earthlink.net/~honda.lioness/id11.html </FONT></A><FONT face="Times New Roman"> . <BR>&gt;&gt;&gt;<BR>&gt;&gt;&gt; <BR>&gt;&gt; <BR>&gt;&gt; <BR>&gt; <BR>&gt; in winter months,gas suppliers change =their mix of volatiles in the <BR>&gt; gasoline,add up to 10% ethanol for absorbing water,and all that can affect <BR>&gt; mileage.<BR>&gt; Tire pressure does make a big difference,too.I've got a slow-leaking right <BR>&gt; rear tire,and when it drops 5 lbs,the mileage drops noticeably.<BR>&gt; <BR>&gt; -- <BR>&gt; Jim Yanik<BR>&gt; jyanik<BR>&gt; at<BR>&gt; kua.net</FONT></BODY></HTML> ------=
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On Tue, 30 Jan 2007 06:32:29 -0500, John wrote:

"ingredients" is that as I said, I have the car since November 2004 and I drove it since then during two winters, two summers, exact same roads and driving conditions....I mean literally nothing has changed.

had an unusual mild December here in New England, so I don't think it is weather related (even if it was unusually cold, I went through two previous very cold winters).

semi-blocked valve or filter) in a way that it will not trigger the check-engine light?

It would be unusual, but certainly possible. If you are unsatisfied with any of the other possibilities, then yes, taking it in for service is probably the best answer.
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Do you want to hear even more? You may call me crazy, but I swear it's true.
All of a sudden, the Trip meter (Trip A) shows that the distance from my home to my office is 16 miles, when it was always only 15 miles.... At the same time, the odometer shows less miles that I should probably have, and I am keeping a good look at that because my car is leased and I am constantly monitoring this so that I won't exceed my 'allowance'. Again, you may think I drank something, I am telling you I didn't.
Is this possible?
<DIV><FONT face=Arial size=2>Greetings,</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>My 2005 Accord EX (2.4L) did average of 28 miles per gallon for two years (since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean </FONT><EM>absolutely</EM> nothing has changed in my driving habbits.</DIV> <DIV>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Then, sometime in begining of December 2006, all of a sudden I noticed a decline of about <STRONG>20%</STRONG> in my fuel consumption...from average 28 to average 22.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Any one experienced this before? Any idea what could it be?</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Thanks.</FONT></DIV></BLOCKQUOTE></BODY></HTML>
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Tire pressure would do it. I noticed on two cars that the tire pressure had dropped by 2 to 3 psi in all 8 tires. The only culprit I can ththink of is the cold snap here in the NE.

and I am keeping a good look at that because my car is leased and I am constantly monitoring this so that I won't exceed my 'allowance'.

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(since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean absolutely nothing has changed in my driving habbits.

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Again - it happened before the cold. December was pretty mild. Also, I checked tire pressure and run a full tank on perfectly inflated tires and got the same results. And I am not talking about a 20% (!) decrease...that's far and beyond a decrerase that you would get if your tires are not inflated correctly.
Greetings,<BR>&gt;&gt;<BR>&gt;&gt;&nbsp;&nbsp; My 2005 Accord EX (2.4L) did average of 28 miles per gallon for two years (since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean absolutely nothing has changed in my driving habbits.<BR>&gt;&gt;<BR>&gt;&gt;&nbsp;&nbsp; Then, sometime in begining of December 2006, all of a sudden I noticed a decline of about 20% in my fuel consumption...from average 28 to average 22.<BR>&gt;&gt;<BR>&gt;&gt;&nbsp;&nbsp; Any one experienced this before? Any idea what could it be?<BR>&gt;&gt;<BR>&gt;&gt;&nbsp;&nbsp; Thanks.<BR>&gt;</FONT></BODY></HTML> ------=
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The two simple maintenance items that most affect mileage are tire pressure and the air filter. The air filter can load up pretty quickly if a lot of sand and salt is blowing around in winter. It's easy to check and replace.
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Yes. As your tires wear and change diameter/circumference, your odometer readings will change.
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Do you want to hear even more? You may call me crazy, but I swear it's true.
All of a sudden, the Trip meter (Trip A) shows that the distance from my home to my office is 16 miles, when it was always only 15 miles.... At the same time, the odometer shows less miles that I should probably have, and I am keeping a good look at that because my car is leased and I am constantly monitoring this so that I won't exceed my 'allowance'. Again, you may think I drank something, I am telling you I didn't.
Is this possible?
===================================================================Possible that you drank something? Oh! I get it ;-)
Yes, I think it's possible. My thought is electrical trouble, but not necessarily easy to find electrical trouble. It could be as direct as a deranged Vehicle Speed Sensor or as off-the-wall as noise on the 12 volt supply to the instrument panel. I don't encourage you to wrap a whole lot of time up in this idea, but a check for AC voltage across the battery or voltage between the engine block and body (both tests with the engine running) would be worthwhile.
If this is odometer foolishness is indeed related to the sudden drop in mpg, it is a lot easier to get the service shop to take it seriously - it is easier to identify and they will know when it is fixed. Really! The trick is to find a preferably known distance and drive it while recording the trip and standard odometer readings.
Mike
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This is inconsistent.The figures you give means a +6.6% error in mileage for the trip meter,and then the odometer has an OPPOSITE error? That doesn't seem right.Shouldn't they both have similar errors?

IIRC,I just read something today on rec.autos.driving about Honda having some sort of problem with odometers accumulating more miles than actually driven,thus effectively shortening the warranty,so Honda was going to add 5% to the warranty mileage limit on the cars.
although this sort of problem would increase MPG instead of reducing it. (6.6% farther distance on a gallon of gas,if he uses the TRIP meter and not the odometer for the miles travelled.)
--
Jim Yanik
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On Mon, 29 Jan 2007 18:14:30 -0500, John wrote:

(since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean absolutely nothing has changed in my driving habbits.

In winter, you have 3 significant factors messing with mileage in Northern Climates.
The tire pressure will reduce, due to cold weather. This reduces mileage. The cold air will reduce mileage a little. And if your gas uses Ethanol (common in cold areas in the winter) your mileage will drop. Ethanol is less efficient.
Between the 3, a 20% drop isn't completely unheard of. Check your tire pressures. There is nothing you can do for the rest. If you had any problems concerning the efficiency of the engine (emissions or ignition issues) you would likely have a check engine light.
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What about 404 Not Found?
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Do you buy your gasoline at the same place? Maybe the gas pump has a error in the computer .
<DIV><FONT face=Arial size=2>Greetings,</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>My 2005 Accord EX (2.4L) did average of 28 miles per gallon for two years (since I got it in November 2004 until about begining of December 2006). I drive the same highway every day, same speeds (average of 75), same distance every day, went through the same seasons twice (summer/winter) in the same place. Nothing, and I mean </FONT><EM>absolutely</EM> nothing has changed in my driving habbits.</DIV> <DIV>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Then, sometime in begining of December 2006, all of a sudden I noticed a decline of about <STRONG>20%</STRONG> in my fuel consumption...from average 28 to average 22.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Any one experienced this before? Any idea what could it be?</FONT></DIV> <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV> <DIV><FONT face=Arial size=2>Thanks.</FONT></DIV></BLOCKQUOTE></BODY></HTML>
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I get as high as 40 mpg on summer road trips and as low as 30 for winter city driving for a civic. Three factors are, 15% ethonal in winter (less mileage), more city driving, less cold weather performance.
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