hey H-T

i have a 96 LX with a bone stock D16Y7, well it has an ebay intake but thats it. i'm the 2nd owner, first was my grandmother, never driven hard or raced. it has all maintenance and new plugs, wires, cap, rotor, fuel filter, and i cleaned out the throttle body. i've been getting anywhere between 18-21 mpg consistently, i think the best i have gotten in the past 2 months is 24 and majority was highway miles. any idea why its so bad? my civic isnt much of an econobox

 

What kind of air filter is it and when/how have you cleaned it? You carry a bunch of crap in the back? When was the last time the O2 sensor was replaced? Has the MAP sensor ever been replaced or tested? Get a maintenance manual if you haven't already. Check the ignition timing and any engine system you've never checked. You can use a big bottle of fuel system cleaner if you haven't before. Changing to better oil can help things along. Auto or manual? Bad brakes or wheel bearings can siphon a little mileage. There are also aftermarket parts that increase mileage.

 

Clean the MAP and TPS, thats an easy start. Are you throwing a CEL?

 

Don't adjust or remove the TPS unless you know it's been messed with before or isn't working correctly.

 

check your timing.
is the engine light on or something?

 

i have no CEL, TPS hasnt been messed with and i dont carry anything in the trunk. its an automatic. i havent checked the o2 because i was told the same thing about it "dont check it unless its been messed with". the only sensor that has been touched it the IAT when i installed the ebay intake.

forgot to mention i only have 78k miles

 

What filter are you using? I ask again because I'm expecting it to be a no-name brand that came with the intake. There's no telling how restrictive an unknown brand of filter is. I'd invest in a big K&N filter. The bigger the filter is, the longer it'll last on your application. You can probably buy one, try it out and return it if it makes no difference. Find out if the O2 has ever been replaced.

 

correct it is the no name filter it came with, idk about it being restrictive but it isnt dirty. i guess i would have to shell out the $50 for a k&n or aem filter in the coming weeks. as i mentioned earlier i'm the 2nd owner, my grandmother being the first. i have all documentation and o2 was never touched as far as my paper records go. i dont remember getting much better mileage when i had the factory intake and clean paper filter thats why i didnt assume much from the no name filter being a cause

 

Thats your prob... you have an automatic... and Im pretty sure you have a lead foot also... I dunno the way you drive but most ppl that get good gas mileage are not the ones that drive 80mph+ on the highway, or pedal to the medal at every light.... Yes even Honda Civics can suck gas if you drive like that. lol There are many factors for gas miles, AC? drive with window open on highway? hilly regions with alot of uphills? I have a fit and if you read in the forum,, just the auto to 5spd manual differences are a good 5-6mpg already..

 

Well if you didn't see a difference and the original filter wasn't clogged then there should be no problem with keeping the new filter awhile. The O2 is old but could be ok. There are electrical tests that can help show its condition. For someone with disposable income I'd say just replace it before it has a problem since it's due and maybe it'll help mpg. Since you don't obviously have money to burn, I'd say spend some time on weekends with a shop manual just checking key systems. Have a look at the timing, check the spark, test the MAP voltage and borrow a compression tester from a local parts store. Once you are familiar with how all the engine components are performing you'll be able to make more educated decisions on what you should put money into first. I've seen a few people with your car get at least 28/40 mpg so I'd expect something isn't quite right.

 

You have the stock wheels on the car?

 

stock 14" steelies as of now, might switch to 15" further on.
i'm pretty convinced its the o2 sensor. i have to check the map voltage and timing, i do have good spark. i know i should be avg around 28 this why i posted this help thread and havent been able to figure it out on my own

 

also, no ac city driving i drive with windows down, on highway i use the a/c and i'm in florida, pretty much all flat. i drive 5 over the limit never more and dont gun it at every light

 

Having same problem with my hatch. Cel code for fuel supply system but replaced injectors and fuel pump is good still. Thinking about trying a new o2 or fuel filter?

 

since you have a 96+ civic, I would say for the most part, your 02 sensor is fine, If it was bad, trust me, your check engine light will definitely turn on. did you put new plugs in? sometimes it could be old worn out plugs.

 

new plugs, cap, rotor, wires and fuel filter. never had a cel