This has probably been posted before but I couldn't find one on search.

I normally get about 400 miles to a tank, but my last 2 tanks were about 300. At first I thought maybe I forgot to reset the trip odometer or something, but the second tank confirmed my suspicions. Can't think of any normal outside things that may have caused this. My oil change is due but that's never hurt my mileage before. There's no leak around my car when it's parked.

Also I want to drive up to NC this weekend, about 500 miles round trip. Is there any reason that whatever's causing my mpg to drop could damage the car on a long trip? thanks Garage!

PS it's a 95 Civic VX

2/16/2010 10:24:00 PM

tire pressure

2/16/2010 11:11:51 PM

^

2/16/2010 11:14:27 PM

Tire pressure and dirty air filter.

2/16/2010 11:23:16 PM

oxygen sensor?

2/16/2010 11:55:02 PM

^

2/16/2010 11:56:14 PM

You get fat?

2/17/2010 12:13:21 AM

fuel filter?

2/17/2010 2:08:16 AM

didn't you do this exact thread once before? it was you or someone, it went on for pages with the OP saying why it couldn't be the tire pressure and then it ended up being the tires were low.

2/17/2010 11:04:59 AM

muffler bearings?

2/17/2010 11:19:27 AM

As someone said above, I have had a bad O2 sensor do that.

2/17/2010 11:19:39 AM

the vx o2 sensor is $$$$$texas

2/17/2010 11:21:50 AM

when the mileage in my accord dropped like a rock after getting wayyyy more mpg than the epa est. i checked everything else and then replaced on O2 sensors. my car uses two. the generic ones were the best price and i just reused the old connectors. mileage went right back up. total spent was around $160. would have been $350 if i had purchased the drop in replacements.

2/17/2010 12:31:08 PM

denso direct fit $41.89 plus shipping part number 23440099 wire length 16.93 in 4 wire.

rockauto.com

does it use more than one?

2/17/2010 12:41:48 PM

FUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU

[Edited on February 17, 2010 at 12:44 PM. Reason : wrong thread. wtf]

2/17/2010 12:44:35 PM

^^

4 Wire O2 was on the CA model of the VX (narrowband).

The rest of the US got a lean burn ECU and a 5 band (wideband) o2 sensor.

I imagine it can be had for ~100-150$.

If you use a random generated o2 sensor list website (like above) you should be prepared for a CEL (I'll be the first to guess it : o2 sensor heater malfunction).

[Edited on February 17, 2010 at 2:30 PM. Reason : L1H1]

2/17/2010 2:27:28 PM

have you checked what you're actually getting mile per gallon wise?

the gas gauge in my 95 civic is pretty haywire.. it's usually fine but it's either not that accurate or my gas tank keeps changing in size. sometimes i get 230 miles, sometimes it's 270..but either way if i figure up the MPG it's about the same..

and how the hell are you getting 400 miles per gallon? 5 speed? my auto doesnt get near that lol

2/17/2010 2:43:20 PM

lean burn, 2000lbs, aerodynamic hatch, light wheels, etc.........................

2/17/2010 2:51:07 PM

^^ that is what i came to post

Quote :

"miles per tank"

this is surely an accurate unit of measurement

2/17/2010 3:17:37 PM

she is the brightest female on this website. i assure you she can do basic division and/or notice getting 2-3 gallons less than usual.

[Edited on February 17, 2010 at 3:41 PM. Reason : .]

2/17/2010 3:41:02 PM

Hmm.. 02 sensors.. haven't though about replacing those before. I should see how cheap expensive they are for the mx3...

2/17/2010 4:07:18 PM

when I fill up I put in 7.5 to 8.5 gallons - that's a "tank". So dropping from 400 to 300 miles for the tank means my mileage is dropping from about 45mpg to about 35. It's a huge drop so something has to be wrong.

I was hoping the O2 sensor wouldn't be so expensive ... that sucks! I'll try all the other stuff first and hope that's not it!

thanks for the advice so far

2/17/2010 10:31:12 PM

My guess is the upstream o2 sensor, and it shouldnt be too expensive if you don't buy oem. They're very simple to replace, too.

[Edited on February 17, 2010 at 11:10 PM. Reason : ]

2/17/2010 11:09:47 PM

Anybody recommend a garage that can change out my O2 sensors?

2/21/2010 5:57:19 PM

did you ever get the problem fixed?
or figured out?

2/25/2010 8:07:24 AM

^^ill do it

2/25/2010 9:17:29 AM