CivicNub

I purchased my car based on the general knowledge and info online that these cars get awesome gas mileage. I'm still getting OK gas mileage but I honestly thought I was in for better than what I have been getting... Right now I'm hitting about 28 highway and a little less city. I was seeing people getting like 35 and 30 so I want to know what you guys suggest. I've replaced both o2 sensors, the fuel filter, did a tune up, tires have good tread and are in good shape... It has stock everything ATM though I am replacing the exhaust manifold due to a crack in it, with headers, new cat and exhaust. My mechanic told me the crack shouldn't be enough to cause major loss in gas mileage so I'm hoping someone can help me out on here.

Former User

A cracked header could definitely make the engine run rich and get poor gas mileage. I think you will get better mileage when the cracked header is replaced. Also check the ignition timing with a timing gun and consider adjusting the valve lash.

What was replaced for the tune up?

Noodler

I got a 99 Ex no engine mods. driving highway at 60-65mph I got roughly 37MPG. I drove 380 miles with a third of a tank left.

Combined highway and city traffic 60-65mph/40mph, i get 32-34ish MPG. Just driving the speed limit will help increase your mpg.

HXor

96 HX 178k miles- mods : full 2.5" Magnaflow catback & fleabay cai. afaik bone stock otherwise. My tank to tank avg is now sitting at 50.4 mpg with a 45/55 city/hwy mix. Does the car "seem" to be running well? dtc's? Have you adjusted T.N.B.T.W. (the nut behind the wheel) ?

CivicNub

It seems to run well enough for stock. I'm not used to having to hit the 4k RPM range in a car to get it to freeway speed in a timely manner so I don't know if that is whats killing me. I'm not out to race but perhaps I should try jumping down in speed as I do cruise at around 80 though it doesn't seem to put a load on the engine when up in that range.

HXor

Under the driving conditions you describe ...you may very well be fixing things that aren't necessary. The EPA revised its mpg ratings in 2008 and if iirc 36/41 are the manual tranny #'s now.
I think if you really want better economy - it is all on you , not the car.

Former User

What engine and transmission?

CivicNub

1.6L non Vtec w/ a 5 speed. This car is so hard to move from gear to gear if I'm not at 4k RPM and REALLY having a hard time w/ it when the AC is on too... Since I'm in CA I have like 0 options for after stock manifold/cat replacement so I gotta buy $400 stock part lol... Anyone have suggestions on getting around buying overpriced stock garbage in CA?

Bo94Accord

i have a 97 lx (d16y7) and i just recently came back from the beach and i averaged 32mpg on the way back but that was going 85mph+ the whole way back thanks to great traffic haha. i do also have a cracked manifold so maybe should get a little better mpg myself but not sure.

by the way you said you were doing headers and exhaust which are you going with and is yours an lx as well?

Former User

I agree that your mileage is low for your set up. I think the cracked manifold is a strong candidate for causing the problem, though I do understand the high cost associated with this repair. A small amount of air entering the exhaust manifold would make the engine run rich.

Regarding the transmission issue, check whether the MTF is low. If so, check for a leak and repair if necessary. Otherwise, drain the MTF and refill with genuine Honda MTF.

pumafeet10

i am a hypermiler who was getting 64mpg and recently lowered my speed another 5 mph and over the course of a 35 mile trip my mpg went to 68.

So speed is one thing that will definitely kill your mileage

Also there is no reason in the world you need to be at 4k rpm ever! unless the occasional race, which you should never do.lol

But seriously i shift at ~2krpm and get up to speed just fine.

I'm sure the exhaust mani is not helping matters.

What about an oil change to lower weight syn and as recommended change your trans fluid

Former User

Can you elaborate on this seemingly unbelievably great gas mileage? Is this a motorcycle?

HXor

True dat pumafeet10! A lot of technique involved hypermiling. Much like a racer, it takes some dedication to achieve Great FE in a car- it can be done.
RonJ check into cleanmpg.com - runwhatyabrung and see what the driver can do 180* from metal to the metal. You can achieve performance And economy in the same car.

NightCat

I'm gettin like 360 miles with 1.8 gallons left in the tank. It's a D16Y8 5 Spd, only mod is SRI.

doesnt seem to be gettin as good as it should...recomendations? just changed oil over to Mobil1 5W30. About to do a tranny flush and fill...

Might replace the fuel filter...tryin to find somethin that is makin me lose MPG's.

yet...could be the fact that I have 135k on the Odo and the car is gettin old and not Operating at its rated efficiency.

Seafoam? BG 55k? Lucas? this **** actually do anything?

AphexMatt

A recent alignment just helped increase my gas mileage by about 3-4 mpg, might be another good thing to have done to yours.

NightCat

Think I need to do that for sure...get some shake at 80+

pumafeet10

as HXor said go to www.cleanmpg.com and you will see i am def not at the top of the food chain when it comes to getting good mileage.

One thing to think about as well, that the warmer it is outside the better mileage you will get.

The longer it takes your car to warm the worse mileage you will get.

So DO NOT warm your car up, get in and drive keeping rpm's at or about 2k and accelerate briskly, don't hammer it but it is good to put load on the engine it will warm up faster and get better mileage faster.

I also do a few things to keep my mileage very high which includes FASing, higher tire pressure, my car is very light weight, and i keep my speed as low as possible

HXor

LOL we're. Both quite a ways from the top! I'll add : read the road ahead and check for alternative routes. Tire psi at max cold sidewall is minimum ... I run much higher on the daily driver and carry an electric pump for adjustments. A tire plug kit in lieu of a spare ..towing coverage is 64 cents a month. Use a 0-30 if in warranty go with 0-20 if out - quality oil filter is a must!