still horrible mpg's

[red98civ]

i was gettting around 190-200 miles on a tank.. which is only about 20 miles per gallon. i changed my plugs, wires, rotor and cap. im almost out of gas and yet again i only have about 185 miles on the tank. i have the pcv valve that im replacing when i change my oil (hopefully this week) but maybe im missing something?
and yes my oil filter was done a month or so ago

 

[Kensai]

Tire pressure? Alignment? Oil change will help a bit too. What kind of gas are you using? Shitty gasoline can decrease your MPG.

 

[1FastEX1994]

^x2

 

[J-Sap]

What mods do you have on your car (if any)?

Is your car throwing any error codes?

Something has to be seriously wrong or changed to be getting 20mpg when most of these cars easily get 30+mpg.

 

[red98civ]

Tire pressure? Alignment? Oil change will help a bit too. What kind of gas are you using? Shitty gasoline can decrease your MPG.

tire pressure seems fine, i'll have to check it again. i got an alignment a month ago when i lowered but im getting another one this week after i replace my tie rod. and i get gas at a sunoco or exxon around the corner from me, i refuse to use the shitty places that are 10 cents cheaper.

and im replacing my air filter on my intake today

 

[red98civ]

What mods do you have on your car (if any)?

Is your car throwing any error codes?

Something has to be seriously wrong or changed to be getting 20mpg when most of these cars easily get 30+mpg.

i have a short ram intake, and i lowered my car and i have an exhaust on it. theres a CEL but its bc i have a high flow cat

 

[jerk334]

what kind of exhaut? running stock headers? low exhaust pressure can lower gas milleage. Do you always do your own oil changes? How many miles on the engine? Could use a good head cleaner for your valves. 20 MPG damn, your like a sick honda. Lmk ill try to help.

 

[RonJ]

-The problem with having the CEL on constantly is that you don't know whether a new code has popped up. Have you pulled the CEL codes recently?

-Have you set the ignition timing to spec with a timing gun?

-Is there an exhaust leak near or upstream of the primary O2 sensor?

-Is the fuel pressure too high?

-Does the engine run cold like the thermostat is stuck open?

 

[red98civ]

what kind of exhaut? running stock headers? low exhaust pressure can lower gas milleage. Do you always do your own oil changes? How many miles on the engine? Could use a good head cleaner for your valves. 20 MPG damn, your like a sick honda. Lmk ill try to help.

the guy i bought the car from put the exhaust on, i know the piping is huge though, way too big. i have my oil changed by my bud who works at a shop. the engine has about 123,000

 

[red98civ]

-The problem with having the CEL on constantly is that you don't know whether a new code has popped up. Have you pulled the CEL codes recently?

-Have you set the ignition timing to spec with a timing gun?

-Is there an exhaust leak near or upstream of the primary O2 sensor?

-Is the fuel pressure too high?

-Does the engine run cold like the thermostat is stuck open?

ill have to have the CEL checked again. i have not set the timing bc im not even sure what that is. i'll have the exhaust checked when its in the shop later this week. honestly idk about the fuel pressure or thermostat or how to check that

thanks for all the input so far everyone!

 

[RonJ]

have not set the timing bc im not even sure what that is.

honestly idk about the fuel pressure or thermostat or how to check that

Start by downloading the 96-00 Civic service manual at the link in my signature. Then get to know your service manual because it is your friend. For example, you will find out how to set the ignition timing and to measure the fuel pressure. If the engine seems to take an excessive amount of time to warm up as indicated by the dash temp gauge, then the thermostat may be stuck open. You are in luck because the service manual will also show you how to replace the thermostat.

 

[red98civ]

Start by downloading the 96-00 Civic service manual at the link in my signature. Then get to know your service manual because it is your friend. For example, you will find out how to set the ignition timing and to measure the fuel pressure. If the engine seems to take an excessive amount of time to warm up as indicated by the dash temp gauge, then the thermostat may be stuck open. You are in luck because the service manual will also show you how to replace the thermostat.

i downloaded it a few weeks ago, just have to find it on my computer.

thanks

 

[RonJ]

i downloaded it a few weeks ago, just have to find it on my computer.

thanks

If you need help navigating around the manual, just let me know.

 

[red98civ]

If you need help navigating around the manual, just let me know.

thanks again! and btw my timing belt is new so the timing wouldn't be off (i spoke to my neighbor who did it for me)

 

[Crutch]

I didn't know that a high flow cat would through a cel. Is that correct RonJ?

 

[red98civ]

something to do with the mass air flow sensor, i forget exactly, its been on for that since i put the high flow in

 

[Crutch]

I don't think that the high flow cat will through a mass air flow sensor but I could be wrong. You may want to change out the mass air flow sensor and just see if that takes off the cel. I know if you get one from autozone and it doesn't help you can take it back.

 

[VSP]

Just another thought: changed your fuel filter lately?

I swapped mine last summer and easily jumped up an extra 5-6 mpg in my light/moderate daily driving routine. Not sure how old it was, but I know I didn't touch it for the first two years I owned my car.

 

[red98civ]

Just another thought: changed your fuel filter lately?

I swapped mine last summer and easily jumped up an extra 5-6 mpg in my light/moderate daily driving routine. Not sure how old it was, but I know I didn't touch it for the first two years I owned my car.

yessir, that was replaced i'd say about a month or so ago

 

[DarkCreep]

I wish I was getting 20MPG's, im getting like 15.