matt69vdub

Hey guys I'm running a bone stock 97 civic ex 4 door with an auto tragic transmission. 224,000 miles on it.

I have recently put a new dizzy,ngk plugs,wires,cap,rotor,airfilter. I also did the seafoam treatment in the intake(this actually improved my throttle response).

I still only get a wopping 24mpg's. The cel isnt throwing anything. It does have an hole in the exhaust right before the muffler(not sure with it being this far back if it could affect anything).

I had a 97 ex 5 speed coupe back in the 90's with a bunch of bolt on crap on it big wheels and such and it got better mpg than this bone stock honda I have now.

Any suggestions? I read in the search that the fuel filter is for life. could it be the fuel filter?

ke98248

iTrader: (1)

Definately yes... I don't know what the interval for changing it is, but I changed my fuel filter after noticing bad throttle response and lagginess from the get go. It helped quite a bit. You could also have clogged fuel injectors/fuel pump.

my 97 civic ex coupe, 5 spd gets me anywhere from 31-35MPG.. All highway is close to 40MPG

Son2BEHO

could be ur catalytic converter and fuel filter and the octane of gas you use maybe something else im not sure though but those aresome more things that can give you bad gas milage

matt69vdub

yeah I suspected the cat but it still feels like it has good power(well good for a civic) and runs very smooth at all rpm ranges. Most people I know with cat problems have a serious loss of power and the manifold will glow red from the extra heat.

I'll go buy a fuel filter,actually I'll look and see if someone replaced the stock one with an aftermarket one. Either way I'll replace it today.

Thanks for the help guys.

CALC!_JUST_du_IT!

with that many miles, i would definitely recommend replacing your fuel filter. next time you fill up, buy premium gas, and get one of those bottles of fuel injector cleaner. try to drive your car hard, till your done with that tank. the higher you rev your motor, the harder the injectors will have to spit out fuel/treatment, cleaning away the carbon build up. you might also want to consider only using premium in your car. it really doesn't cost much more the regular, and it gives you better mileage, and yields a healthier motor.

ke98248

iTrader: (1)

Also, low tire pressure.

ke98248

iTrader: (1)

There's no need to buy a higher octane fuel than 87 unless you're boosted or have some serious motor work done to your car.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ke98248 &raquo;</TD></TR><TR><TD CLASS="quote">There's no need to buy a higher octane fuel than 87 unless you're boosted or have some serious motor work done to your car. </TD></TR></TABLE>

Yeah, octane is irrelevant unless your compression ratio is pushing numbers that it will pre-ignite if you use lower octane gas. This usually happens under boost or a stroker motor. 87 will work 100% fine for ALL USDM '92-'00 Civics.

@ OP:
Throw a different O2 sensor in there for awhile and see if it changes. Sometimes they go screwy and throw off mpg without throwing a CEL, if it doesn't improve, obviously that's not the problem, nothing lost, put your old O2 back in.

Then from there, without a CEL, you might have the same problem that I think I'm having - and that's that an injector's hanging up and not closing.

There was a dude on here awhile back who had a B20 swap in his CRX and was getting like 11mpg because 2 injectors were jammed open. Only sometimes that throws CELs, sometimes it doesn't. Check the O2 first.

highrev1987

a car with two injectors jammed open would throw a constant flame lol

matt69vdub

Anyone know what the flow rate of the stock injectors are? I have some old 14lb bosch injectors off of one of my old bmw's that I could throw in there.