quote:

I have a 97 D16y8 with 120k miles on it
only engine mods are AEM CAI and i run 89 octane gas with Castrol GTX 5W-30 syntec blend
i have noticed a signifigant loss in gas mileage since i put the AEM CAI on. no matter how i drive (even though i am at WOT all the time) i get around 25-28 mpg at best
before i put the CAI on i was getting 32-37 mpg depeding on how i drove. i put alot of highway miles on the car. i recently put a can of retore in with my oil change, and heard a NOticable amount of vaccuum increase( through the Bypass of the CAI, i can actually here it sucking air in at idle now, while standing over open engine bay, neverheard it before i put the restore in) but i still havent noticed an increase in gas mileage. i know it takes a few tanks before the Restore really starts working. but i am curious as to why my gas milage is so low? i know with the AEM CAI it is a lil more responsive, and i drive a lil harder cause i LOVE hearing VTEC kik in at WOT. but even when i drive like a grandma on highway i still dont get an increase in milage. the Best i can get on a tank of gas is 300 miles. i used to be able to get 400 (still leaveing one gallon of gas in)

what should i do? should i run HIgher OCtane Gas? ie go to 93 or Sunoco's 94? IF i do that will i not be able to go back to 89 octane with out getting pinging? (old myth) i recently had my TIming bElt replaced, and i am guessing that honda reset the timing back to stock 16 degrees i think.
should i advance my timing? like by 2 degrees? will that help with gas mileage as well as make the engine more responsive?
should i advance timing AND run better gas? will that increase the gas mileage, repsonsiveness, and make the car run quicker?

Thanks in Adnvanced
Dan

 

unfortunately any aftermarket intake will decrease mpg same with many other mods, 25-28 isnt bad on a civic, u sure u got that much b4? advancing and retarding the timing can have unpredictable results as far as gas mileage goes, it depends on ur driving style on which way would yield more mpg, unfortunately with modifications done to ur engine expect to get worse and worse mpg. but our little hondas should always get a good 22-25 mpg as long as uve still got a n'a setup no matter how bad ur setup may be

 

it is really hard for me to me to comprehend how 1 mod such as the AEM CAI can cause a 10 mpg drop in milage. its not like i supercharged or got any REAL advantages from the CAI.

just because the engine is now sucking in COlDEr Cleaner Air it gets worse mpg? i understand the part of me always riding the gas so i can here the intake ROAR(hahah im pathetic) but if i drive like a granma u should figure it would get better milage.

 

Start simple, I would make sure your spark plugs and your cap and rotor are in tip-top shape. On previous cars that I've added an intake to, mileage actually increased with the same driving habits and no other mods.

 

Engine gets more air, you need more fuel for proper ratio reading by o2 sensor.

 

This is true, but the engine is able to ingest the air easier compared to the stock shaker box and resonator, which helps make more power and means that you spend less time accelerating, and more time at cruise RPM, which is where you use the least amount of fuel. Again, I have seen fuel mileage go up with the addition of an intake if everything else is in good order.

 

yah it all depends on ur driving style and the mechanical condition of ur car, with everything running efficiently u shouldnt see a drop newhere near 10mpg maybe 1mpg but thats about it.

 

When I replaced my spark plug wires for 9mm ones I noted a significant increase in gas mileage. On a drive that would normally cost me approx 40$ in gas... I was now paying btw 30 and 32$.
I'd check that if I were you... More air from the intake means more fuel and so you need more spark to keep things balanced and efficient.

 

the higher the octane the farther advanced your timing can be before detonation.....assuming you're not getting any now check your timing and see where it really is - if you go up in octane you could bump it up 2 degrees or more depending on how close you want to come. pinging really only shows it's ugly head at high rpms ..your fuel map and timing will be very different up there - basing the results there with static timing is about the only way you have to experiment , but beware - detonation is a bad thing.