HELP! mpg is too low

[Kalindian]

Hello, i just bought a 1998 Honda Civic EX with 85,000 original miles. Its my first Honda and I think I am not getting the right mpg. After 2 fill ups, I'm only getting 19-21 mpg , this seems way to low. I have replaced the oil, tranny fluid, spark plugs, wires, rotor cap, and will be replacing the fuel filter soon. My question is, what else can I do to increase the mpg? The car sat a while so i think there may be carbon build up, but i don't know weather to use bg44k or seafoam or what. Also, the car runs great and doesn't burn or drip oil. Its an awesome car, I just want to increase mpg. Thanks for the help!

 

[speedygonzales]

bg44k is good stuff plus its easier to use than seafoam... just pour the can in a full tank of gas and you're good to go. Also check your tire pressure... that right there will kill your gas mileage if its low

 

[SGGilmo]

may be bad fuel as well depending on how long the car sat for. first thing you should always do when buying a car that has sat for a while is drain ALL the fluids and inspect them for debris.

 

[Kalindian]

I am going to replace the spark plugs again because I found out i put in way better plugs than i needed. Could this make a difference also? Thanks for the reply's by the way!

 

[RonJ]

auto or manual?

 

[zachkelly]

have you been running the air conditioning or accelerating really quick? Both of these probably wouldnt dip the mpgthat low, but it sure wouldnt help

 

[lowlife9]

replace rhe oxygen sensor.

 

[Kalindian]

RonJ, Its an auto. I may have to replace the O2 sensor, but its not throwing any codes so i don't know if its gone out or not

 

[lowlife9]

just because theres no cel code doesn't mean the oxygen sensor is not over due to be replaced i believe its every 90,000 miles.

 

[MistahJuice]

Is there any lag between when you press the gas pedal and it accelerates? If so check your timing, may be off. My mpg was down to like 22 avg when my timing was at 6btdc and it shoulda been at 16btdc. Now I'm back up to 30's when I baby her

 

[Kalindian]

MistahJuice

Is there any lag between when you press the gas pedal and it accelerates? If so check your timing, may be off. My mpg was down to like 22 avg when my timing was at 6btdc and it shoulda been at 16btdc. Now I'm back up to 30's when I baby her

Yea, there is a small lag. But it is really small, and btw, I was just reading your build thread. Its looking good!

 

[Kalindian]

Update: After changing the fuel filter and running the car with 89 octane for a tank and doing some highway runs (80+ mph) the mpg has increased to 29-31 mpg. Which is where it should be. Also, I used some STP fuel injector cleaner with that last tank i filled up with and that also did wonders for my Civic.

 

[MistahJuice]

Sweet glad you got it all worked out man. And thanks for the compliment

 

[emerican]

glad you got it worked out man
if it sat for any period of time id drain flush and replace every fluid in the car possible just to be certain

 

[Kalindian]

glad you got it worked out man
if it sat for any period of time id drain flush and replace every fluid in the car possible just to be certain

We did, they all have been removed and replaced