i have a 1996 civic ex coupe with 224xxx miles on the odometer.
despite having a lot of miles my engine runs really well.
i'm replacing the rear main and oil pan gasket soon (they leak about 1 quart every thousand miles).

but here's the problem:
on average i get about 24 mpg. i can get almost 30 but i have to go slower than grandma slow and i can't rev it past about 4k rpm. oh, and it has to be almost entirely highway too.

on the car:
AEM short ram
really decent no name header
apexi ft spec 60mm exhaust (and no, i didn't pay $1000 for it to go onto a D Series lol, i got it from a friend for cheap)
new fuel filter (10k ago)
new oem distributor
new ngk plugs and wires
new cap and rotor
new IACV
new TPS sensor
stage 1 exedy clutch

did a compression test 130psi all around (stock is 135)
leak down test read:
(left to right)
5 - 10 - 11 - 8

i'm not sure why but i'm getting well under what i should be for mpg... nay help would be greatly appreciated!

 

Your engine is old and unhealthy. Refresh it.

 

i want to eventually, but currently it runs fine...
it seals well (the pistons i mean lol) and is smooth so i am inclined to argue that.
not to be rude, but thanks

 

how many miles since you replaced your O2 sensor?

 

both of them have less than 10k on them

 

...and grumblemarc might be right...
i just hope it's not time yet...
and i don't really have the money right now to get a Y8 either lol

 

They're not much at all... you can find them on Craigslist, just the engine, for about $200. On average, it would probably be more like $300, atleast around where I'm from.

 

yeah, about the same here... it sucks though cause it runs like a champ...
just isn't very gas friendly...

 

...how hi do you guys rev to in daily traffic?
cause under 4k my car has minimal power and doesn't really accelerate with traffic as easily

when i'm trying to be efficient as well as drivable, i like to shift at 3500-4000 - it drops to about 2500 ish

 

Doubt if you want but 135psi is the MINIMUM compression for a healthy engine.

 

yeah... grumblemarc you're right.
he's getting pretty tired i guess.
time to swap and restore.

thanks guys, really.

 

Check your cat could be getting clogged .

 

the cat i replaced a week and a half ago... lol sorry - didn't put that up there

 

You shouldn't have to rev it up to 4k to keep up with traffic. And if I remember 135 is pretty low. I'd say it's time to rebuild or find another engine.

 

Did your cat blow chunks into the rest of the exhaust? Could be clogging it up quite a bit. I had that problem with mine.

 

yeah, i'm pretty sure you guys are right...
it's old and tired.
when i have the dough i'll replace it.
thanks guys for the help

 

soooo.... come to find out my header was too big (in diameter), leaked from the gasket right off the block, and also it blew out the gasket between the 4-2... SO, i replaced it with the "better" stock y8 header from the 99-00 model years (mine's 96). and my MPG went up some - probably 3-5 mpg depending on how i drive. - i guess it was having trouble scavenging and the O2 sensors and stuff.