Is it worth it to keep my cold air intake?

when i first got my 2002 Hyundai sonata i was still in school so i felt the need to spruce up my car with a few upgrades such as a cold air intake, high flow muffler, new radio, etc.

now because i have the 2.4l version of my car no aftermarket intake exists for it.
however over the years i have built and rebuilt my intake making it better every time.

now here’s where it gets interesting, about a month ago my cars gas mileage made a huge leap without me changing anything, after getting around an extra 80 miles out of my tank i noticed that my air filter had fallen off.
i assume that my filter falling offhad caused better airflow and thus better gas millage.

now i’m not real big into modding my car any more and was thinking about buying a stock intake for my car(lost the old one)
or would it be better to keep my current design and just buy a bigger filter to have that extra air flow?

also what is the best/worst case scenario for my filter having been off fro about a month on freshly paved rock roads?

PS. its not really a cold air intake more of a cone filter intake, the filter in in the same spot as the air box used to be

"what is the best/worst case scenario for my filter having been off fro about a month on freshly paved rock roads?

The worst case scenario is that your Mass Air Flow sensor (MAF) is now so dirty and crudded-up that it will need to be replaced. The best case scenario is that you will only have to clean the MAF.

I am not going to comment on the rest of your post except to point out that you may have a hard time selling the car with an aftermarket CAI on it, as it tends to mark the car as one that may have been “hotrodded” and driven hard. If I were you, I would restore the original intake system, but others may disagree with me.

Think sandpaper. That’s what that gravel “dust” being kicked up and sucked into the cylinders of your engine is doing to the cylinder walls. You’re driving in a worst case scenario every day. Get a filter on there no matter what. My 4¢…

“I noticed that my air filter had fallen off”? How did this happen?

I agree with VDC. I’ll add that while I suspect most of that mileage increase is placebo, largely due to an improper mileage measurement method, it’s possible that the MAF is not sensing the actual amount of airflow and you’ve been running a bit lean. The MAF is one of the signals that tells the ECU how much fuel to add.

I agree with TT’s commentt as well. Grit getting drawn into the engine can do no good, only harm.

In addition to VDCdriver’s comments, I would like to add that you should change your oil ASAP. It is probably has, suspended within it, dirt that the air filter would normally keep out of the engine. I would also use a bottle of fuel system cleaner in the fuel tank next time you fill up, and maybe clean the throttle manually with some carburetor cleaner.

The others have already addressed the problems, so I’ll address the intake. I, personally, would leave it on there. It’s probably not doing jack for you as far as performance goes (homebrew intakes can often be better and cheaper than commercial ones, but you need either dyno data or amazingly good luck to achieve this), but it’s probably not hurting things either. A straightpipe intake like what you have described will generally make you slightly slower off the line because it’s more susceptible to heat soak from the motor, it will make your car louder because you’re no longer connected to the intake resonator, and it will probably give you a bit more hp (we’re talking 4-5 here) which will compensate for the sluggish start. In short, all it does is make your car louder, but it doesn’t usually harm performance overall. As such, it would be a waste of money and time to buy and install a stock intake. Throw a filter on there, and change the oil as the others have recommended, and keep driving. And tighten the hose clamp down more this time :wink:

I have some difficulty believing you got an extra 80 miles out of the tank just because a filter fell off, unless your filter was incredibly dirty. I suspect something else contributed to it. Any number of factors could be at play here: Driving location, style, city/highway mix change, air temperature, barometric pressure, fuel quality, etc.

And measuring method. Measuring mileage based on how much you get per tankful is just about the most inaccurate way you can measure it, inless of course you let the tank run completely dry each time. It’s impossible to tell how much gas you have left in the tank at any given point along the fuel gage’s travel. Irregular tank shape alone means that the surface of the fuel does not drop in a linear fashion, and things like what angel the car is parked at and gage damping make the inaccuracy even greater.

I have already changed my oil and used some Techtron in my gas tank, so i’ll probably clean my MAF sensor tonight and hope for the best.

i get my millage by how many gallons of gas i put in my car, i had let it run down to about 2 gallons left and filled it with about 15 gallons.
and my millage was at about 350 (normally 270) which is still a good 5 mpg higher than it should be.
which your most likely right the MAF is probably dirty making my car run lean

as for why the filter fell off in the first place, bad hose clamps loosening over time.
that should hopefully be fixed now.

Than I guesss I misunderstood how you’re measuring mileage. Apologies.

If you’re using an oiled filter, I’d replace it with a dry one. Oiled filters have been known to mess up MAF sensors.

nice tip thanks