hall97civic

I have a 97 honda hx w/ 5 sp and d16y5. Completely stock. I have done a tune up and have ran a tank of fuel system cleaner and for some reason I can not get my mpg's over 40 again. When I first got the car(going on 2 years ago), I could mix town and highway and easily get 38, now I am getting 32-34. When I'd drive just highway/back roads I could get 40-42, now I am lucky to get 37. I don't drive like a bat out of hell either. I used lucus oil's fuel system cleaner first, now I am trying techron. I was contemplating getting a k/n drop in air filter. Anybody have any proof that it increases mpg's? Let me know what you guys think I should do to increase mpgs. Like previously mentioned, I have done a complete tune up not too long ago (ngk v-power plugs, plug wires, cap, rotor, fuel filter).
later

kieran84

could be any one of many things, timing mite be a bit off, some of your sensors might be gone. you need to check all these. you getting any engine management lights? is the eml working???? my friend found his had been taken out....

sde780

I've been getting 22 mpg in my 98 lx, it sucks.

I have the K&N drop in filter, didn't do anything.

I've changed fuel filter, air filter, tire pressure, and I drive REALLY lightly.

Still, *22* mpg! I hate my car

dipsy

try replacing ur o2 sensors and getting ur injectors cleaned at a professional place.

hall97civic

ok, update. Just got back in the house. I checked the tappet clearence and they all were within spec except one exhaust valve (#2 cylinder, 4th exhaust valve from timing belt). I haven't touched my timing. I have done a t-belt change and it would still get the good milage. I also checked the plugs out and they look good, maybe running a bit lean, little bit of grayish tint...not the dark brown like it should be. Also did a compression check, lowest one is 183 psi so we are more than within spec there. The car/engine/tranny all have 144,000 miles on the clock. I am currently running 5w30, when it gets hot out I run 10w30. I use castrol 90% of the time, and penzoil any other. I change my oil and filter every 2,000 miles, just when the oil starts to change away from the clean brown. No CELs. The only cel's this car ever has had since in my possesion is random miss fire due to a plugged egr plenum and then egr malfunction due to me unplugging the egr valve till I fixed the clogged plenum. All CEL's are from about 2 years ago when I bought the car. So as you can tell I take care of my car and the only other thing that I can figure is that the plenum is filling up with carbon again or the injectors are getting dirty or wore out. Is it worth buying new injectors?
tell me what you think guys.

hall97civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dipsy &raquo;</TD></TR><TR><TD CLASS="quote">try replacing ur o2 sensors and getting ur injectors cleaned at a professional place. </TD></TR></TABLE>
I really don't want to spend 300 some dollars on o2 sensors that still work properly. I have been thinking about getting the injectors cleaned though. Anything else that I can do myself?

slacks

seafoam your cars
1/3 in gas tank
1/3 in crank case
1/3 in brake booster
it'll help clean everything out and that might help
just be sure to change your oil after your do crank case and brake booster

hope that helps

dipsy

thats how much urs cost?? it costs 50 bucks brand new for my DC. Also they may still work but years of driving causes carbon build up and affects readings. GL on getting more bang for the buck.

hall97civic

obd2 o2 sensors are expensive, also there would be 2 that I'd have to buy.

hall97civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slacks &raquo;</TD></TR><TR><TD CLASS="quote">seafoam your cars
1/3 in gas tank
1/3 in crank case
1/3 in brake booster
it'll help clean everything out and that might help
just be sure to change your oil after your do crank case and brake booster

hope that helps </TD></TR></TABLE>
I've never had much luck with sea foam, except for cleaning out your fuel tank and plugging your fuel filter. But that's just my experience. Trust me my crankcase is spotless. Look how often I change my oil . I might try runing some through the intake. We'll see how much free time I have this comming week. Will that be hard on my cat at all? What about carb/throttle body cleaner?
later

hall97civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kieran84 &raquo;</TD></TR><TR><TD CLASS="quote">is the eml working???? my friend found his had been taken out.... </TD></TR></TABLE>

what hte hell is 'the eml'???

nub

with 144k and your still getting over 30 mpg you should do a backflip and knock on some wood. its sounds like youve maintained your car well, keep it up and be happy with your milage (178k 35 mpg avg. here) or buy a prius.<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hall97civic &raquo;</TD></TR><TR><TD CLASS="quote">obd2 o2 sensors are expensive, also there would be 2 that I'd have to buy.</TD></TR></TABLE> honda/acura 4 wire o2 sensors are all the same except for the length of the harness

NOFX

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hall97civic &raquo;</TD></TR><TR><TD CLASS="quote">what hte hell is 'the eml'??? </TD></TR></TABLE>
EML = engine maintenance light.

hall97civic

makes sense now. thanks.

teal_dx

5 speed HX's use a wideband 5-wire o2 and cost a couple hundred bucks
I know, I had to buy one and didn't even end up needing it

hall97civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nub &raquo;</TD></TR><TR><TD CLASS="quote">with 144k and your still getting over 30 mpg you should do a backflip and knock on some wood. its sounds like youve maintained your car well, keep it up and be happy with your milage</TD></TR></TABLE>

The only problem that I have with this post is that my compression is at or on the highside of the factory range. Trust me I have a honda service manual and 180 is normal, 200 is high, and I am right in the inbetween range. Oh, for reference 160 is the low side. So the only real good suggestion I have right now is to get my injectors service/cleaned. Would it just be worth buying new ones? Comeon, you guys have to have more tips than this!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teal_dx &raquo;</TD></TR><TR><TD CLASS="quote">5 speed HX's use a wideband 5-wire o2 and cost a couple hundred bucks
I know, I had to buy one and didn't even end up needing it </TD></TR></TABLE>
and thankyou for this reply, this means that I am not insane! lol

fastrc2

check tire pressure and alignment. may sound odd, but at the same weight on them and same size tire and pressure, certain tires have more rolling resistance than others. how much extra stuff is the car carrying. your mileage may have been 40 but iff you compare to the epa, 37 city 44 highway is what was originally states on the window sticker. i speak form experience, i have a 1998 hx 5 speed, and i have gotten 49.8 on the highway once. but i normally get mid 40's without airconditioning, and also ensure that you accelerate slow and shift early. i am not trying to teach you anything or make fun, just helping out with what experience i know. as for what you can do to improve what you have, i dont think it needs any parts or anything. if most any part was bad it would have a significant effect on the mileage, probably enough so that the car would really drive.

hard_boiled_EG

sounds kinda dumb but shifting early really does help with gas, i have a 92 vx hatch, and it has the little green arrow which tells me when to shift, i tried it on a full tank of gas once and got 350 almost 400 miles to the tank...considering the way i drive and the mileage on my car right now, i usually get 300 maybe a little more if i'm lucky... if all else doesn't work, try some RESTORE it works...

jmeyer99

Your car is running good! Those are good mileage figures...particularly if driven in COLD weather. Makes 10-20% difference.

hondamark35

no injectors. you only need to add stuff to your fuel tank at your tune up, not on a regular basis. if you want to clean that stuff out put mid-grade or premium in. that little bottle of stuff has the same conditioners as the premium from the pump. and the premium likely has more awesome stuff. (on a side note, mid-grade is regular mixed with premium..)

you can use seafoam if you already have bad buildup in your engine (and you can tell if you do by just glancing in the oil fill hole with a flashlight. it's a pretty quick and easy representation) but if things are clean all you need is fresh oil, which you said you do already.

i did notice improoved highway mileage after installing a short ram on my, then stock y7. and, though i have no hard numbers or proof, i believe switching to the y8 exhaust helped free up the motor a bit (reducing pumping losses, to put it in tech terms.)

yeah, tires, alignment.. brakes are a big thing. you can have drag on your rotors or drums and not know it. have them checked and adjusted by an experienced specialist (or do it yourself if you're familiar with the tecniques). you do want to confirm your ignition timing is in range. i wouldn't worry about the cam timing if it seems to have normal power.

Endo-land

I second the cold weather notion, up in the frozen arctic where I live it can very almost to 6mpg when it is -15 degrees out.

hall97civic

Hey, how long does it take your guy's cars to warm up? If I let mine sit and idle, it won't even make it into the normal range, and if I just get in and drive then it takes it about 3 miles to get to were it normally runs(half way in the normal range). So I am thinking about replacing the thermostat because it's cheap and easy, but messy). Also, I very seldom shift over 3,000(unless I'm having fun), usually around 2500-2700. I don't get on the throttle hardly at all and usually shift when the shift light says so. Tire pressure is at 35 psi all the way around, brakes are good. Um, what else....and the car drives and stops straight(don't have to hold onto the wheel, it can drive itself until it hits a bump or something). Anything else guys/gals?

hall97civic

one last bump.

spray_bombed

I've noticed a slight increase in my 96 hx since I've adjusted the valves....mine were sloppy as ****....but I'd say give that a try...and I know what you mean with the expensive *** primary 02 sensor....

old man neri

Few things.

Yes, cold weather affects your mileage, it is out of your control. In certain areas the fuel is diluted with anti freeze agents. Just accept it.

Don't let your car sit and idle with the heat on to let it warm up, you will waste fuel. Get in it, start it, let it idle for maybe 30 seconds, and drive gently with the heat off until it warms up. That is the best and quickest way to heat up the car.

10W30 oil? I use 5W20 year round in my 98 hatch, that is what honda recommends for me.

35 PSI seems like a lot of pressure, especially for the rears.