Celica Forums General Discussion Engine and Performance Is my CAI lowering my gas mileage?

Ok, so when I got my GT brand new, my mileage was averaging in the low 30's per gallon. Granted, 75% of my driving is done on the highway. The only true power adders I have installed are my AEM CAI and my TRD exhaust. Lately I have noticed that my mileage has been significantly lower. I'm talking in the mid-low 20's!! So then I went into troubleshooting mode. I cleaned my air filter, cleaned the MAF, changed the spark plugs, cleaned the throttle body, and changed the oil. I have kept up with all the maintenance. Yet, my mileage doesn't improve. I do have roughly 62,xxx miles on my 2002 car.

I just got back from Atlanta cruising down I-95. I got 300 miles with 3/4 tank of gas. That's high twenties, maybe even 30 mpg. It should be better.

So now I'm thinking it's the CAI. My hypothesis is that since the AEM unit is a quarter inch larger in diameter than the stock air intake, more air is getting into the engine. With more air means the MAF is telling my car to add more fuel to go with the air. I've read up on the Blue Bomber hybrid intake setup, and I'm wondering if that improves gas mileage. Because technically, the only amount of air that is getting into the engine is the amount of air the throttle body is letting in, which is sized to math the 2.5" intake pipe of the stock unit. So I'm thinking if I hybridize my intake so that the MAF is mouted on a piece of 2.5" pipe after the 2.75" AEM pipe, the MAF will start to act correctly by adding the right amount of fuel for the right amount of air.

Does this make sense? Has anyone solved this problem?

I was thinking the same thing when I had my CAI on my other Celica . oh well i'm working on a new project 98 Towncar

I don't know, why worry about it? We drive INLINE-4's, i don't think it matters. I get gas basically everyother week during a normal week in my 6sp GTS, and it doesn't bother me.

more fuel or air = more hp, so ill let you thinka bout it, and plus our cars get almost 30 miles/gallon why do you care...

Only had my GTS a short time and got 33MPG city the first week. Granted not inner-city but still it's share of stop & go. I'm ecstatic. My Excursion gets 12! Don't even want to know what my BB Vette gets.

im gettin 40mpg in my GT

I care because my car was once making 30mpg, but now is around 20mpg. Do the math. That means I'm using 33% more fuel at a faster rate. So instead of filling up once a week, now I'm filling up twice a week. At $20 per fill up, that means in a year I am spending $1040 more on gas than I use to. That's money that could be used for more mods.

And though you may be right with your little equation, how much more horsepower am I really getting, 2? 3? 4? The Celica's computer is robbing the car from producing better horsepower than what people get from adding intakes and exhausts.

mine gone down from 28 to 25mpg...and it's a 2000 gts...i don't think i drive that hard...dunno y

in that case crbn blue dont do any engine mods so you wont waist more gas then and take of the CAI so you could get your 30 mpg again oh yeah your exhaust too & sell them

was gonna say the same about for the reason of the gas loss. Maybe now you have a cai you push the gas harder because it response better too?

why are you guys telling him to do this and that and trying to be a smart "alex". If you don't know the answer to the question then don't post.

CRBN BLU, I don't know the answer to your question but maybe try and do a full fuel system tune up.

when my cai is on I get like 22 - 24 mpg, when my stock box is on I get like 25 - 28 mpg. More air = more fuel = more power = more gas = more fill ups = more money spent.

I get 30-34 mpg highway with my gts and i have an exhaust and sri.

i have a cai on my corolla and i cant tell a diff in the gas milage...its pretty much the same. in your case though, if your really worried about it, just get an Safc2, but if your that worried about gas, why do you even have an intake?

Run some fuel injector cleaner and clean for MAF sensor.

I noticed a difference!

That has to be the stupidest fucking thing I've read in a long time. Believe me, I know the deal: cause and effect. Cause: I add performace mods to the car. Effect: power goes up and fuel efficiency goes down. Next time, keep your $.02 to your self.

Again, the only reason I'm so concerned is not that there IS a difference, but at how LARGE the difference is. I'm concerned about a larger problem.

i dunno about ur gas problem but i do know that gas prices is f*cking ridiculous @ 2.26/gal here..i'm sure you guys are paying atleast 3/gal..man that sux..i fill the tank every single week..

For regular (87 octane) here in Tidewater, VA it's averaging about 1.99/gal. For premium (93 octance) it's about 2.19/gal. And it's on the way up. I'm fortunate enough to have a GT and only need regular

Gas milage changes with the seasons. Gas in the winter is not the same gas in the summer. There are different additives for different temperatures outside. I know that this affects the MPG of cars, but I don't think that it would be a 10 MPG drop. Maybe like 3 MPG, but not 10. I put my Injen CAI on, and my 28 MPG never changed.

There are many things affecting fuel mileage besides your intake. I don't know all the dynamics about how air pressure, temperature, and humidity affect an engine, but I'm pretty sure it does. Driving style can also make big differences (my first tank ever on my car was 23 MPG, because I floored it at every light, but now I'm getting around 30 with slightly more than half of my driving on the highway); it's possible that some weird quirk in everyone else's driving habits is forcing you to spend more time with your foot down, without you necessarily realizing it. Any traffic jams, different city driving conditions, unusual traffic light timings, or even pump problems (not filling all the way) can cause problems with your gas mileage. I'm sure there are other factors I don't even know of.

Going from 30 to 20 MPG is a pretty big drop though.

No offense, but maybe you're not calculating it properly? Always good to rule out the easy stuff...

I agree with whoever recommended a fuel injector cleaner, but otherwise keep an eye on it. If it gets worse than maybe you do have a problem.

How many weeks have you gotten this mileage? When did you last change your spark plugs?

i'd assume with the addition of the cai that you'd be driving more aggressively (higher rpms & more acceleration) rather than shifting at 3000 rpms for better fuel economy.

if you're so concerned 'bout "miles per gallon" then changing your driving habits will drastically alter your consumption (however reducing you to turtle's pace).

the cost of gasoline isn't that expensive (more than recent times but still just nickels & dimes) and if your budget is extremely limited you have to either increase your revenue or reduce driving time.

First, I have an automatic, which should provide better gas mileage for the Celica. Second, when I determined I was getting 30+ mpg, I was driving the same way I am now. As far as seasons are concerned, I would think that winter driving would be better for the car since the cold air helps keep the engine cool and provides a denser charge for the incoming intake air.

I just got gas today. Took 10.702 gallons of gas for roughly 250 miles of traveling. Using higher math, that's 23.36 mpg. Granted, I did drive a bit rougher than usual these past couple days. It was a race weekend, so I spent some time with OverDrive off.

I'm going to try the fuel injector cleaner and go from there. Any reccomendations on brand, product, etc?

crbn blu, it sounds like you are startin to pms, we are only tryin to help you!
we dont need all these sarcastic comments like "the stupidest fucking thing i've read" and "using higher math", you want to hear about higher math be a engineering major like me and take the highest maths there are!

i say again, we are only tryin to help you solve this problem, if you dont like some of the answers or dont agree with them, you dont need to trash them!

have you taken it to the dealer and asked them yet since we cant seem to find whats wrong and worst comes to worst go back to stock and get your 30mpg back!

Woah, son. The reason I got mad is because rather than try to help, some people post stupid comments that are of no help. That's why I get mad. It's an all too common problem on the boards. Do I need to read, "If you care so much about your gas mileage why bother with performance mods," and much of the contents of your post. And for future reference, I am an Applied Mathematics major with a double minor in Biology and Political Science, so I can confidently say that I've taken all your math classes, and then some. So cut back on the ego trip!

I hate to say it, but do a search to find a good brand of fuel injector cleaner. My mechanic (whom I would trust my life and my car to) used BG 44K or something like that.

Have you changed your spark plugs at 60K miles? I read up on this and bad spark plugs can cause a drop in gas mileage.

haha, i read this like last week and was contemplating it the other day while i was driving. A few things people said are wrong i believe, 1) CAI does not increase airflow to engine, a N/A engine is only gonna take in the amount of air of the displacement each revolution, and the air is not going to be forced into the engine like turbo application, so the same amount of air will enter the engine. Yes, colder air is slightly denser but not to the effect it will manipulate gas milage. 2) the typical problem with CAI is running lean and that is what the "blue bomber mod" helps to correct by providing an accurate reading, if your getting poor gas milage it is from running rich not lean.

I figured out what my problem is. Turns out, I need a new O2 sensor. Since it's on the outs, it probably is affecting my gas mileage. This is what I was worried about in one of my earlier posts: that something more was wrong. The reason I know I need a new oxygen sensor is that my car threw a CEL and it lead back to the sensor. So now I need to replace the sensor and hopefully that will return my mileage.

the colder the weather, the more gas you will use. air becomes more dense in the winter and therefore, requires more fuel for a proper combustion to suite the computer. the opposite goes for summer, which is why you will get a slightly faster time in the winter than the summer, and also a little more hp in the winter. depending on when you did the mods, this could be a reason why, and also, a manual will get better gas mileage.

Not on our car, for my GT:
MILEAGE ESTIMATES GT (VVT-i) GTS (VVTL-i)
Manual (city/highway) 28 / 33 23 / 32

Automatic (city/highway) 29 / 36 23 / 30