Sledneck

My roommates 2000 civic auto sedan has 70'000 mi and gets terrible mileage. It gets about 270-310 miles to a tank of highway driving(driving about 65-75mph). This seems terrible to me for a civic (its ether a dx or ex, cloth interior, power windows, heated mirrors).

The car also starts hard, by starting hard i mean cranks a lot before starting. This is relative to the temperature as well. When its -17F, the car could crank for 10-15 sec. around freezing about 5 sec.

No check engine light, and the fuel filter was replaced about 15'000 mi ago.
The car warms up quickly so the thermostat should be good.

Now my roommate isn't the smartest cat, he drove around without a gas cap for about 20'000 mi and he doesn't drive that car easy either. I bought him a gas cap at about 62'000 mi.

I'm going to replace the air & fuel filter, but do you guys have any other ideas?

MelJ

That doesn't seem too bad considering the weather. I barely get 25mpg in the winter compared to 34mpg in the warmer weather(thanks corn industry!). Have you tried putting gas line antifreeze in the tank for each fill up? It's bad to run a tank all the way to the bottom in the colder months as it takes more gas to turn the car on, and you run the risk of freezing the gas line if there is some moisture in there(which is why I mentioned the gas line antifreeze). If he drove around with no gas cap, wouldn't that throw a CEL?

BlueEM2

iTrader: (1)

Time for a regular tuneup. Just your basic stuff like spar plugs, wires, cap+rotor, air filter. Youd be suprised how much of a difference it makes. I get 33MPG on my civic. So basically with 40 liters I get 550 kilometers. roughly. (350 miles per tank)

MelJ

A word of advice on the rotor if you go about the tune up. It has a special screw and I ended up breaking my rotor to try and get it off. You might wanna invest in a pair of side cutters. The blades should be thin enough to slide under the screw to start unscrewing it. I had to find this out the hard way .

sdaidoji

iTrader: (1)

that seems about right mileage for driving and season... and if OP up north (guessed from his avatar and username...), it's bound to be hard to start anyway

Sledneck

Ya its a Canada EX, motor is D16Y7. and ya i live near Calgary, Alberta.

I rechecked and the filter was changed at 31 000 miles (50000 kms) so its due.
I checked the air filter its clean.
I scanned the car no codes

Ill buy a fuel filter, PVC, and change the oil(its due). See how the PVC and fuel filter effect the mileage.
If no difference ill consider wires and rotors.

I never driver the car in the summer, so I'm not sure how it's mileage compares.

It seemed low to me compared to my other buddy who get 600-700kms (434 miles) out of his.

marek91

what year of civic ex ? if its 99 - 00 it should be d16y8 and 96 - 98 i believe are d16y7

Newfiedan

if you have done the tune up and its still hard to start in colder weather then I would be looking at the coolant temp sensor that the ecm uses, usuallay there are 2 1 for the dash gauge and 1 for the ecm not sure on civic though either way it will not throw a code if its reading still however the resistance could be way off and when the car first goes to start it reads that sensor to determine the starting air/fuel mix. I have run into this problem on several cars and that was the cause, get a multimeter and check the resistance cold and hot then compare that to the manual. The d16y7 is the nonvtec motor the d16y8 is the vtec motor.

Steven21

Well these cars do not start very well when low on gas and can take a while even when you think you have a decent amount of gas in the tank. Personally my car gets about 27 mpg in the snow but about 35 in the summer. Its nothing to really worry about unless this was happening when it starts to get warm

MelJ

It sucks doesn't it. Steven21?. At least my gas mileage is about the same as yours.

Steven21

its awful i was seriously worried about it at the beginning of the winter but once it warmed up for a couple days it was back to normal. this winter has been killer on my car this year at one point i was driving around on our roads with snow above the front bumper while at stock height!! it was like a mini snow plow lmao and i might add that it pushed right through the snow.. this is also a great car in the snow

Sledneck

Update:

It is a D16Y7 I read it off the block, and it is a EX im 100% sure.

I replaced the fuel filter and it starts way easier.
Im now getting about 600km(370mi) to a highway, i calculated between 27 -31 US mpg

Newfiedan

new fuel filter is considered part of a tune up lol, at least you got it working good now.

marek91

it cant be an ex or a 2000 lol cause it should have vtec then . . . and it should be a y8 unless the motor was swapped or it was re-badged ? lol is the trim painted ? as well as the mirrors ? the same color as the car or is the trim/mirrors black?