Fuel Efficiency Drop
 

Curious if I need to look around and see if I have any problems, so thought I'd get some opinions.

Stock my truck was getting around 17.5 MPG with 87 Octane. After installing my Airaid MXP CAI and 18" Mufflex Muffler and switching to 89 Octane I just averaged 15.1 MPG on my first tank (hand calculated). I want to see if another 2-3 tanks will change but so far it doesn't look good according to the computer. I think my city MPG has dropped but highway has gone up. I was under the impression a CAI and new muffler would increase fuel mileage, not decrease it. Also could be my driving habits changed, lots of factors but would like a general idea of others experience. Thanks.

Did you unhook the battery after you installed that junk to force the computer to relearn?

Besides, if it were possible to actually increase milage with $10 worth of plastic and tin, don't you think that the manufacturer would do that from the factory?

Maybe, remember the factory is required to meet not only emissions requirements but also noise requirements. This includes intake and exhaust. Making either of these more efficient also makes them louder.

I unhooked one terminal like the directions said when I installed the intake. Should I have unhooked both? I thought I read somewhere that you have to be careful when you do this because it will mess up the radio or something of the sort.

What about the weather. I see you are in Houston. Way outta my realm so I have no idea what the weather is like there (I know it is several latitudes south of me),but a 15* drop costs me ~ 1-1.5 mpg while hwy cruising. Also, dealers are switching over from summer gas to winter gas right now. I have read that winter gas nets lower mpgs, but that is just heresay.

The weather took mine down a little, but in houston I would have to think it is still warm.

Ya if you have the REN radio it was an actual Service Bulletin that says to remove the fuse for the radio before removing the negative battery cable (the only one you have to remove to reset)
I have no faith in those CAI's, I spent over 400 for a KN on my 03 Durango, sold it a few months later when I realized I was losing on average 2 miles to the gallon. I was told by a mechanic who is keeping up on technology unless he wants to go out of business, said that some vehicles will save gas, get better HP but others the computer sees more air, sends more gas. So if you don't use a programmer on it you are not gonna save. I made 100 bucks, sold it to my Quebec connection, this guy bought anything I bought and didn't like, he was afraid of buying things with credit card.
Back to CAI, I tried one on a Dakota with 4.7L same thing. Now I did all this before I was told about a tune or a programmer or sending my ECU somewhere to get programmed. I just wondered after spending all this money how long will it take to save that money and now that it sounds better it sound even better at WOT so that is part of the equation LOL>

Oosik,

Nice to see another Fellow Houstonian on here. from my understanding is these trucks are all computer controlled and it could take a little while for the truck to relearn again after the mods. and it has been a little chilly lately that could have made a difference also.

Update:

I unhooked the battery for a couple hours last night and pulled a couple fuses and plugged them back in. Hoping to reset the computer somewhere. What I've noticed and I think is happening is in city driving or anything under 40 mph, the CAI doesn't get the proper air speed going through it, so it's basically useless. Anything above 40 mph is great, I had it reset and drove to work this morning with little traffic and capped out at 20.2 MPG before I got to work. It does drop when I accelerate which I'd expect, that's where the computer is saying more fuel for the increase in air, but highway cruising speeds are ideal. It makes me sad though because that means traffic is what's killing my mileage.

@Gaorenst

I swear I'm the only blue 2009 quad cab, I don't have all the extra chrome like a lot of people. I like the fact my truck is unique even though it wasn't top of the line, my first new vehicle purchase.

That's the best quote I've seen in awhile.

This reminds me of an arguement I had with a lady one time. She had moved over to a new building and the traffic light was programed by the local Kindergarten class (not really). She was spending about twenty extra minutes a day sitting at that light and she just couldn't understand why her fuel mileage had dropped off so much. I told her that she was using more gas sitting at idle in one spot at the light instead of using it for forward momentum. She jumped up and down me saying that I had no idea what I was talking about because fuel mileage could only be calculated when moving and not sitting idle.