jlaustill

Ok, so I bought a 1992 Honda Civic LX after reviewing them on fuelly and finding that people were averaging about 38mpg. My first tank I got 20mpg, but this car needed a major tuneup so I didn't think much of it. Now that I have done the tuneup, I'm getting about 29-30mpg, but not 38, so my question is what should I be looking at for possible reasons? Here's a list of what I have done to it already, and a link to the fuelly history after 4 fillups.



I have done

Plugs/wires/cap/rotor
adjusted timing(it was off by a LOT)
fuel filter
air filter
cleaned throttle bottle/iacv, then adjusted idle screw(was all the way out)
recharged A/C
replaced VSS(speedometer now works "sometimes")
replaced all vacuum lines, did smoke test, no leaks
replaced timing belt/all accessory belts
new battery
new brakes/master cylinder
rotated tires

Ok, so yes, it's been an expensive month between all that maintenance and buying the dang thing haha. SO, all you long time honda civic owners, what should I be looking at next?

crazyhouse2011

Buddy, is it a 5 speed or a slushbox? if it's the slushbox then be grateful for that 30 mpg. If it's a 5 speed, then don't worry, you are just adjusting to the new clutch feel. It took me 2 months before I could confidently launch my car (I always could DRIVE it, but it was a little unnerving to launch for a couple weeks). And as much sense as this will make, you get better mileage on the interstate than in the city. I usually keep the revs below 3 grand in the city, but on the interstate they are at 3300 revs! You would think that would guzzle gas, but I get 31 or 32 mpg, even though the car is 18 years old! (as cars age they lose their efficiency). My EX was rated at 31 mpg highway from the factory. ANYWAY.... it sounds like you are on the right track. i wish i had the money to do all that stuff in such a short time. My only suggestion is try a dash of SeaFoam. It gets mixed results from people, but I always get good ones, and it is hella fun. Look around for info on that, but if you want MY low down on it, just ask. A can of seafoam will run you about 10 bucks. good luck mate.

jlaustill

Yes, important details, doh. It is a 5 speed, I bought it strictly for the economy, so I wouldn't have bought it if it were a slushbox Cars do not generally loose mileage as they get older though, mythbusters did a thing on that They do loose compression over time naturally, and lower compression lowers mileage, but my engine has GREAT compression, especially for one with 250k+ on it. I have a properly maintained F350 with 362k on it that gets EXACTLY the same mileage as it did new, but it certainly wouldn't if not properly maintained.

That is the biggest reason I just simply replaced the vacuum lines instead of trying to track down leaks. Generally speaking vacuum lines are one of the single most ignored maintenance issues in vehicles. I've seen people replace every single sensor in a car and rebuild the engine to find out they just had bad vacuum lines

That being said, I have never owned a Honda before, so I'm more or less looking for advice from people with experience on what tends to fail on these cars. For instance, if it were a Pontiac Fiero, I would instantly do a complete tranny flush as they have a tendency to gum up and get REALLY bad, and I would replace all 4 wheel bearings as they have a tendency to overheat the brakes and ruin the wheel bearings, both issues add up to bad milage over time.

But I have NO idea what the little issues are with my civic, so I'm more or less fishing

crazyhouse2011

Pointers: Hondas like to rust. They love it. especially around the rear wheel wells. My buddy has a 89 accord with some rust above the rear wheel, and bubbling paint on the other side in the same spot. My car was hit pretty hard with the cancer. you should check out my pictures to see how it progressed from being rusty to solid again (albeit a little ghetto looking). i'm gonna see if i can upload an entire 65 picture sequence in an album to show all the body work i did to my car. Rust also goes for the underbody. Jack up the car and take a look below. My floorpan looks EXCELLENT. not a hint of rust. just factory metal. I'm 250 pounds and when i stand in the back seat there isn't a groan or a creak to be heard. But the engine bay is different. there is a good deal of flaking on the oil pan, as well as the suspension components. For god's sake i had a brake shield rust so badly it fell OFF the car and sat inside the steel wheel for 4 weeks making a very loud WHOOSHING noise as the wheel turned. i finally jacked up the car to see what the noise was and BAM this sickle-shaped rusted out piece just falls to the ground. Damn....

Just to pretty things up i would go to a local dealership and have them clean it up for you. the dealership i work at charges 36 bucks for a full clean, inside and out. Although it is somewhat of a ripoff, i can give you some advice.
Degreaser. Get some degreaser. Put a plastic bag over your distributor and your battery and make sure they won't come off. spray a whole can of degreaser on your transmission and engine, and anywhere else dirty. let it sit for 5 to 10 minutes. Then power wash it all out, or use a garden hose and taper off the end with your thumb (power washer is WAY better). It made my engine bay look so much better. The transmission just had so much gunk on it that it looked, well... OLD. But the degreaser cleaned it down to the bare metal again. Good stuff. Next, I would paint your valve cover. you can do a factory gray, or you can get creative. I painted mine with caliper paint a vibrant red. then I sanded off the lettering to give it a badass honda look. Once again, you can find a few photos of this in my profile. Let me know what you think!

Former User

Any CEL codes? Does the CEL work?

crazyhouse2011

I WILL SAVE YOU THE TRIP TO MY PAGE. Here is a before/after picture of my engine bay. The one on the left is the day I bought it. The one on the right is what it currently is at. Amazing what a good sanding, scrubbing, and a few chemicals can do.



I uploaded my album of bodywork pics. I had to skip a few pics towards the end. An album can only hold like 58 or so pictures. I have 72.

jlaustill

CEL light works like a charm, it was throwing a VSS code when I got it, put the new VSS in and hasn't thrown any codes since. It runs GREAT now that I tuned it up, I'm kinda shocked how much get up and go it has for a 1493cc engine! I am starting to get the feeling that my cat might be a bit plugged, but I have never known a clogged exhaust to not cause CEL's with o2 codes. Then again, Honda seems to have made a pretty darn amazing engine/computer combo considering that it ran with the timing retarded by about 30 degrees...

Crazyhouse2011, your valve cover looks SICK!!! I have a bit of rust spots on my rear quarters, but after your little speech I did some googling, apparently it's even got its own nickname in "honda rot," thanks for the heads up, I'll have to get my civy up on a lift and check it out good! I'm actually gunna be getting the engine compartment/undercarriage professionally detailed here soon. I already got the interior/exterior detailed and man did that make a world of difference!

crazyhouse2011

Well done. you are officially on the road to professional Honda ownership.

dirty19

iTrader: (1)

How anyone can expect 38mpg from a 18 year old car is beyond being realistic.
If you wanted that kind of economy you should of been looking at a much much newer car.
If you are getting 30 thats pretty darn good considering your chassis has probably close to or over 150K on it.
This whole mythbusters thing is BS because it was a general study not a study for all cars in general.
Not everyone has the same driving style and truth to be told you cant 110% regulate how you drive everytime you are out on the road.
Other factors weigh in on how one drives.
Rest.. are you in a hurry to get home?
Traffic are you in stop and go traffic?
Music you are listening to.. That angry music, jazz, or easy listening?
Welcome to honda ownership, but worrying over the difference in 8mpg on a 18year old plus car is just asking too much for what you have,and what you paid for it.

Former User

My 97 Civic DX sedan 5-speed consistently gets 33 mpg in mixed hwy/city driving.

If the OP's D15b7 engine is in good shape and properly tuned up, and the car isn't driven hard, then I think a 35 mpg expectation isn't unreasonable.

94AnaHonda

^ Agreed. If you included factors of age and music (wtf..) and other kinds of miniscule things that 'could' hinder the gas mileage then they would account for those in the 'estimated' mpg from jump. OP, seafoam is a hit or miss, some like it some don't. You may look at your cat if you feel it's clogged, could be a problem and could hinder gas. My 94 Ex slushbox maintains 29mpg regularly and I drive it like a bat out of hell and it's got roundabout 200lbs plus of stereo in the trunk. Lot's of people say 38 mpg is what they get a lot and it IS feasible in your particular car but realistically those people are probably driving 45 mins round trip to work everyday. Some don't equate distance traveled by highway versus city. I round trip to work everyday a 38.5 mile trip, if I do nothing but travel to and from work for a week I can get upwards of 32 mpg (not bad for auto) and downwards of 26 ish if I run through the city a lot. You may try running a cleaner through the tank and even possibly a tad through a vac line, see if you don't get a lil change.

pityocamptes

Could also be the type of gas you are getting. Most fuels are cut with ethanol. May want to see what percentage your's is, at your location. Ethanol with destroy your mpg... other things like elevation, etc. can all play a part...

Former User

The gas I run contains ~10% ethanol.

kyden

is it driving habits? my 97 4 door integra ls gets 33ish combined city/highway. If I do all highway, 38mpg isn't out of the question.

70mph average speed on the highway, and always very light on the throttle when accelerating.

94AnaHonda

Same here. Considering I'm only about 5 hours from Ron. LOL. Driving habits I tend to think only account for 2-3 mpg maximum, I mean unless you're full throttle for 5 mins every single time you get in the car then the fuel loss for "smashing" on the throttle every ONCE and a while shouldn't cost you a lot of gas. That is also a variant based on power of the motor (based on fuel supply demand). Looks like you've got a bit of hit or miss playing with things OP. Compression test? All cylinders fine? No serious clogs?

Former User

The OP could also check whether:

• the engine is running cold (stuck open thermostat)
• there's an exhaust leak upstream or near the O2 sensor (false O2 sensor readings sent to ECU)
• the brakes are dragging or the wheel alignment is off

Also, what is your tire pressure?

Telecatster

Mine is 98 civic ex coupe .. 25 mpg city and 35 mpg highway. Assuming you got your estimation in this way(s): http://www.fueleconomy.gov/mpg/MPG.do?action=calcMPG

The gas gauge in older civics are not accurate (as any left turn will tell you). Mine goes down below the red line before the yellow caution light comes on.

crazyhouse2011

SEAFOAM WORKS. TRUST ME.

jlaustill

To the previous poster, I'm sure driving habits are a LOT to do with it! I tried running one tank of gas babying the heck out of it and got WORSE mileage, so I'm running my current one stepping on it pretty good to see how that compares. I'm sure just figuring out how it likes to be driven will be a good portion of it.

I'm running 38psi in my tires, they are rated for 44, so I could up it a bit, but I'm not sure that would make a huge difference. I just did the brakes, wheels aren't dragging, and it's cycling up to temp just fine.

An exhaust leak is a real possibility, I'll have to check that out along with looking for rust. I also noticed it pulling a bit to the right today, so an alignment is needed for sure. Seafoaming it can't hurt I suppose, and it does have a boatload of miles so I'll add that to my list.

So on the agenda now is

Alignment
check for exhaust leaks/being plugged up
seafoam the heck out of it
try a different gas station
Learn how to it likes to be driven

I'll check back after those, but my budget is stretched SERIOUSLY thin at this point, so it won't be today

Thanks for the input everybody, I think I'm getting a handle on this...

X E Ryder

On higher mileage engines that may have a carbon buildup, I have certainly had good luck with Seafoam, following the directions. For what it costs it won't hurt and it may help cleanup that cat a bit.

Telecatster

crazyhouse2011 is a real meh-CAN-ic.

joumama

could changing out your wheel bearings help? do people generally only change wheel bearings when they start making noise? i would think that wheel bearings that are worn out or lost their lube to them may cause a great deal of drag. Also , I have a fourth and a fith gen model, and weight defenately makes a big big difference as well as what kind of tires you are running, wider tires are going to give you a huge difference in drag and rougher handling. on my fourth gen civic i get the best mileage due to it's lighter weight as well as the fact that i just have the stock small skinny tires that it came with. although they don't look as sporty, i get the best gas mileage out of them as well as a preetty smooth ride out of them.

crazyhouse2011

I bet those internet memes provide quality education.

strategy400

37 mpg on my '95 del sol w/ 318k on it and that with 50/50 stop and go and ~80 mph.

jlaustill

Wheel bearings and tires are two of the biggest causes of drag for sure. I am running stock size 175/70r13's, but they probably aren't the lowest rolling resistance tires I could buy. I checked all 4 wheel bearings and they seem to roll just fine without any noise. I plan on replacing the rear two to swap to disks next time the thing needs breaks, I guess I'll see if it makes any difference when the day comes

I live in Montana, and it's kinda funny how many high school kids buy a truck and save up and through 35's or bigger on it. THEN find out that they get 2mpg and blow their engine up from all the overuse lol. One kid I went to high school with(it's been awhile, shhhh) put a 4' lift, yes four FEET, and some HUGE 40's that were super wide, I really don't know the exact size, but they came up to my chest! These were on a Chevy 1500 with a stock v6, it smoked soooo bad and went like 20 mph top speed and eventually died. Not to mention you needed a ladder to get in, and would have tipped over if you hit a speed bump lol. Oh the memories lol