gas mileage? what mileage

[85wonderwagon]

Hey guys im a 3g civic lover but my daily driver is a 4th gen wagon. My wagon gets horrible gas mileage, and I have no idea why. I did a tune up on it(plugs,wires,rotor,cap,airfilter,oil,oilfilter,) and it did great like it use to for about a week then it went back to crappy @$$ mileage. I reset the ecu and babied the hell out of it. The only thing that changed is that it idled better, and still no gas mileage. i spend about $60.00 a week in gas and its starting to take a toll on my savings, so please any help would really be appreciated.
thanx

[sastanley]

Have you calculated the mileage you are getting? I just got 36.6 MPG this past weekend.

Try new plugs and cap/rotor/wires. Bad/weak spark can contribute to poor mileage. Also double check your timing and make sure it is not screwed up

[4-Door Flunky]

My 90 sedan got 38mpg when I bought it at 75,000 miles, and is now getting 30 mpg at 175,000 miles.
Give us some hard numbers, dude!
Flunky

[91civichatch2571]

Originally Posted by 85wonderwagon

I did a tune up on it(plugs,wires,rotor,cap,airfilter,oil,oilfilter,) and it did great like it use to for about a week then it went back to crappy @$$ mileage.

He already replaced the normal stuff. Id say get your system pressure tested, make sure none is leaking from anywhere. $60 a week is pretty nuts depending on how far you drive.

[sastanley]

shit - my bad.. - sorry dude...I didn't see he'd done all that.

[RedRacerCivic]

well my car gets measly 15-20 miles a gallon, but thats due to a big compression leak in #2 cylinder

[i_a_n112784]

I know this isn't the right generation, but my 94 civic cx w/ rebuilt dx engine (35k on engine) gets insanely high milage, it will seriously get 40's for mostly highway driving.

Some of the problems could be caused by high milage, stuff just stops working as well as it did at 30k miles. And don't foget that some milage loss can be caused by a dirty air filter, low tire pressure, and tire wear.

Wear only matters a little, but as the tire gets worn, the diameter of the object the moving changes, slightly throwing off your speed sensor, and odometer. Larger tires do the same.

Just throwing suggestions out there.

[4-Door Flunky]

Really bad mileage can be caused by a clogged fuel filter.
Have the valves been adjusted recently? I'm just trying to come up with any other possibilities here, although when valves are out of adjustment, usually you just hear them clatter....they don't really bring down the mileage that much.
I suppose you've checked the air pressure in each of your tires, and looked at the recommended pressure printed on the side of the tire?
Low air pressure in the tires is the number one reason for poor mileage.
Flunky

[91civichatch2571]

I suppose you've checked the air pressure in each of your tires, and looked at the recommended pressure printed on the side of the tire?

Not to pick on you or anything, but thats not really true. I know its kinda anal but the actual recommended psi for your specific car is usually writen on the door jamb. But another thing that would effect gas mileage could be that the car needs an allignment. If your tires arent toed correctly, it creates quite a bit of resistance when driving. Caster and camber wont make much of a difference at all gas-mileage wise, but toe would.

[85wonderwagon]

I was thinking could my o2 sensor be fried??? possibly? My car isnt loud or anything but i was thinking maybe it was shot? I dont know. I Havent really dealed with the milage problem before. Thanx guys

[sastanley]

the o2 sensor will certainly affect the efficiency of the car. Normally, you'd get a check engine light, and the corresponding code would indicate the O2 sensor is not functioning. Another thing I'd try is to reset the ECU and see how that goes. I normally do that when I do things like a major tune-up or add/remove bolt-on parts. There are a couple of ways to do that, I just pull the battery gorund off for about 5 minutes. I think there is a fuse under the hood (near the battery) for the ECU too..you could pull that so you don't have to reset things like your radio and stuff...

[bambam89lx]

Originally Posted by 91civichatch2571

Not to pick on you or anything, but thats not really true. I know its kinda anal but the actual recommended psi for your specific car is usually writen on the door jamb. But another thing that would effect gas mileage could be that the car needs an allignment. If your tires arent toed correctly, it creates quite a bit of resistance when driving. Caster and camber wont make much of a difference at all gas-mileage wise, but toe would.

Actually, that's not true. U should follow the psi on wutever tire and wheel you have on ur car. Ur not gonna follow the recommended psi on ur door jam when ur crx is rollin on 18's with low pros are you? No. That recommended psi in the door jam is for stock size wheels/tires. Also, every tire is different with how many psi it needs. Even two tires of the same size could have different recommended PSI. I would suggest letting all the air out of ur tires then refilling them to the correct psi labeled on each tire (in case you have different tires).
Also, do you blow black smoke from ur tailpipe? Have someone rev ur wagon while you look behind it to see if there is black smoke coming from it. If there is, you can be running really rich which leads to poor gas mileage. A bad O2 sensor can affect this. Last, u should test ur compression with compression guage. low comp. can affect mileage as well.

[sastanley]

I don't want to get into the whole tire debate since dude was asking about gas mileage, (although improperly inflated tires certainly be a cause for poor mileage, but if you have one or two that low, you have bigger issues to worry about. I saw a guy driving around yesterday (in a Mustang ) with a tire as flat as a pancake...and that bitch was all torn up indicating he'd been driving forawhile on it...can't people feel that?

I don't follow the recommended inflation pressures on my door jamb either (I think mine is actually in my glove box and it says 26 or 28 psi) I personally think that is for the grannies that want a nice cushy smooth ride. I run the max PSI on the sidewall so my shoulders don't wear down when I drive like an ass - I have had some Pirelli's (stock size) that had a 44 PSI max pressure rating..but usually the max is 36 PSI for "regular" non-performance passenger car tires. I run my Yokohamas at about 38 PSI, and the Michelins in the back about 35.