[chrome2386]

I have an 03 automatic with around 34,000 miles. The only engine mod is a Cold Air Intake from americanmuscle.com Feels like ever since I put this on I have watched my gas mileage drop drastically. I am getting around 11-12 city highway is also a laughable 19. So that has broken down to around 70 miles or so to the half a tank. Now I am open to any suggestions to make this work better. Do you think the CAI is just screwing up something!?!? and that stock would be better off. I have a sub and 2 amps in the trunk but that was in before the CAI and bad mileage. HELLLLLP!

[hotshot]

Maybe you are running very rich. Also try cleaning out your MAF sensor and doing a tune-up. Properly inflate your tires as well.

[poultry411]

Absolutely, check what you touched last. Make sure you didn't damage you're MAF sensor either by improperly cleaning it or shock damage. Look if you're connections are still good too. Has you're driving habits changed? Are those highway numbers with or without cruse control?

[chrome2386]

Hotshot - What would be the best way to clean my MAFS? I check my tires periodically so I know thats good to go. Maybe a tune up would be a good idea, can't hurt to try.

Poultry411 - Connections are all tight except I noticed when I first placed the CAI together, it had an extra rubber opening. Any idea what that could be for? I have nothing lose to plug and I'm thinking that possibly could be effecting the gas consumption. I am actually a lot easier on my car than I was when I first got it. The most highway driving I would do I use the cruise control. Usually set it between 65-70mph (which I know is not the best for fuel consumption but gotta keep with traffic).

Thanks for the help so far!!

[chrome2386]

OH yeah and forgot to mention I have a flowmaster setup, which the previous owner had put on terribly because I bottom out like crazy. Went to see if it could be fixed...I was told to let it fall off and then replace it...ugh

[poultry411]

Originally Posted by chrome2386

OH yeah and forgot to mention I have a flowmaster setup, which the previous owner had put on terribly because I bottom out like crazy. Went to see if it could be fixed...I was told to let it fall off and then replace it...ugh

Well... I'm betting thats you're problem! if it's been bashed and battered it probably is leaking. I went from 25 to 19 on the highway when my manifold cracked. The 3.8L is touchy about it's back pressure. I even lost power when it cracked. If it sounds like crud, thats probably the cause right there. There is also a TBS out on the passenger side manifold. It cracks because the cold water from the AC drips onto it. Hot metal... cold water.. not good. FYI if it did crack, thats not carbon steel. The manifold if 304 stainless steel and you need 304 or higher rated filler metal to weld it.

PS- is that rubber thing the grommet that's meant to help attach you're CAI?? It's some sort of vibration dampener for the original intake, and the CAI kits reuse them.

Brainfart.... hey, is that rubber port still open? If it is, it should be plugged off, especially if it's after the MAF sensor.

[chrome2386]

Poultry411 - I am taking my car to a local shop to get it on the lift to see if there is any leak, doesn't sound like one but possibly could be. I read many places about the back pressure being a problem with the V6s so I hear ya on that. I do hear the condensation from the AC leaking and making a "tiss" sound when hitting the hot metal. Didn't think it was that big of a deal...being that I don't run the AC that much and only 34k miles I am hoping that it did not crack. The rubber opening is between the manifold and the MAF sensor. I guess plugging that somehow could help but still confused as to why it is there...maybe older models have something to place there. There is also another opening but I plugged some cable into it (no clue what it is for).

[GuitarstarX7]

Make sure your cats aren't crushed when you are checking under your car. The CAI shouldn't have any openings. It might have been an extra opening for an air temp sensor that I think some mustangs had.

Sometimes the brand of gas can effect your gas milage. I noticed with shell that I get more miles per tank!

[ewells2420]

plug up any extra holes ASAP! there should be NO open holes in the cai system. And yes depending on your year there are extra holes for different years. I too have an 03 V6. There should be 1 hose comming from the intake manifold to your CAI and thats it. Any other holes, tubes, open anything should be plugged ASAP.

Air that isnt measured by the MAF will KILL your mpg.

[Sixer01]

Could you of possibly touched the MAF sensor? I would clean it first.

[StalkerStang]

Originally Posted by ewells2420

plug up any extra holes ASAP! there should be NO open holes in the cai system. And yes depending on your year there are extra holes for different years. I too have an 03 V6. There should be 1 hose comming from the intake manifold to your CAI and thats it. Any other holes, tubes, open anything should be plugged ASAP.

Air that isnt measured by the MAF will KILL your mpg.

Although I agree, if there is a opening that large thats not being metered, the check engine light should come on. That would cause a major lean condition, but yeah plug that damn hole before you do anything, go to a parts store or something and get a grommet or something.

[chrome2386]

I plugged the hole up and gave it a new tank of gas. Checked the mileage and got a bit better to 14.5 with like 30 miles highway and 80 city. Should I disconnect the battery and then connect, let the car run for a bit without driving. A friend told me that car can then relearn everything...does that make sense or have no effect?

There is no exhaust leak so that is not one of the problems. A few of you mentioned cleaning out my MAFs but I really have no idea how to do that. What would be the best way to go around doing that?

[StalkerStang]

Makes it easier for the computer to learn it over. But driving it long enough should return it back to its original state if that was why it was running so bad.

[poultry411]

well, most of you're driving is city, that right there will kill it, especially if you are in traffic w/ the AC on. Definitely plug the hole, but there may be another sensor going south on you. If you run out of options, try doing you're services like fuel system cleaner and new filters all around (clean the CAI filter). You could also try a new o2 sensor in the manifold. Just because it's barely seen miles doesn't mean it's not been chillin' for 5 years since papa ford put her together.