jordan88

hi i have a 98 civic ex coupe d16y8 with aem cai and cat back. in summer i used to run up to 560km per tank, but since winter is colder, which required more fuel to warm up the engine, so its usually around 470-500km per tank, but for some reason i am down to 380km this time, what could be the problem?

fuel filter?

thx

CivicSiRacer

Colder weather is more dense with oxygen so you need more fuel to go along with it. Also check your tire pressure to make sure they are up to par, since cold air contracts so your 35psi might be 28psi now.

SRT_Andy

Do a tune-up and see if that won't increase your gas mileage. Spark plugs, cap, rotor, engine, fuel filter, and air filter. Also, if you have over 45,000 miles (you convert into Km), you need to replace the transmission fluid. Also, put new windshield wiper fluid in, that'll defnitely decrease the wind resistance by lowering the amount of bug intestine on your windshield!

twistdCivic

whoa dude, you get some damn good mileage. i get 380km on a good day, and my car's all stock.
but anyways, yah try a tune-up first. and you're getting 380kms regularly right?? not just once??
btw, its more accurate to base your gas mileage using the averages of miles/gallon, or kms/liter, not kms per tank.

93DituneEX

I'm getting worse than that and have no clue why.......? What all do they do in a 100K service? I have a aem cai and fairly new fuel filter and plugs, what could be my problem?

twistdCivic

yah my plugs, fuel filter, air filter, cap, rotor, etc. are fairly new too... yet my mileage is crap. so i dunno?? maybe 02 sensor?? FPR?? engine oil? tire pressure?? your driving style?? lol... i have no clue man... im trying to figure it out for myself too but i just dont have the time.

tommytoes

Have your driving habitts changed? Aggressive driving can definately impact you gas mileage as well as what kind of commute you have......ie...highway or bumper to bumper.

Jafro

Chances are, your IAT sensor (Intake Air Temperature) is out of range because it's so cold. It's normal for some cars with CAI's to actually throw codes in the ECU in the winter time (depending on how picky your ECU is) when the IAT sensor is reading out-of-range. It has a lot to do with adjusting your fuel trims, and a cold air intake makes your OEM IAT read even colder until it warms up.

After sitting in sub-freezing temperatures overnight, and when I warm mine up, it throws code 10's (IAT) constantly. After that, it's fine. Mine blows black smoke (fuel trim too rich) if you romp on it before it warms up. It also gags the spark from all the extra fuel - making it stumble and misfire. I swapped the IAT sensor from the old motor to see if I had a bad one, but it did the same thing with both of them on 2 different days.



I've gone from 325 miles per tank in mixed driving to getting as low as 260 per tank since the on-set of winter in VA.

You were getting 347.2 in miles per tank. That's about 35mpg, and that's damn good. Now you're getting about 235.6. Yeah, uh... I'd worry, too if I lost over 100 miles per tank. That's a pretty big drop. Definitely check it over. How about your tires? When the temperature drops, so does your tire pressure.

white_n_slow

my milage gets pretty bad when its time for a valve adjustment.

twistdCivic

really?? i didnt know needing a valve adjustment can affect your gas mileage. that might explain it for me, because i need one.