Anyone get worse mpg after Cold Air Intake?

[99ls1z]

Have a 07 LTZ with AEM CAI and magnaflow muffler. Put the intake on shortly after I got tahoe about 6 months ago. My average mpg is around 13-14 with mostly city driving. I haven't thought much about the mileage until a couple of other friends have tahoe/yukon with same 5.3 that drive the same route as me and they are average 15+ mpg. Theirs are completely stock. I know driving style can make a difference but I drive mine trying to get better mpg. I always run 87 octane but have tried 89 last few tanks and mileage is the same.

Just wondering if it has something to do with the intake/muffler? I would think I would get better mpg with those mods.

 

[JennaBear]

Are you tuned for the intake?

 

[NathanJax]

Are you tuned for the intake?

This.

Jenna will explain better, but to just throw an intake and exhaust on could hurt more than it helps. With a good tune you will see a big difference.

 

[DStockton]

I think they are worthless.

 

[JennaBear]

The are worthless on a stock tune.

 

[99ls1z]

I don't have a tune. Could this be why my mileage seems lower than a stock 5.3?

 

[JennaBear]

Yes, for two reasons:
One, torque output at lower rpm is usually reduced slightly with an intake
Two, on newer vehicles, the MAF becomes significantly out of calibration

Depending on the intake, that can either cause an increase in mileage due to higher ignition timing (similar to how a tune increases mileage )or reduced mileage due to reduced ignition timing.

 

[Denali0229]

I just put one on my truck and I have the BB tune. I can definitely tell it makes a difference in power but haven't noticed any difference in gas mileage. I actually thought it improved a little but this last tank I'm back down to 10-11 mpg which is what I was getting before BB tune and intake.

 

[NathanJax]

I just put one on my truck and I have the BB tune. I can definitely tell it makes a difference in power but haven't noticed any difference in gas mileage. I actually thought it improved a little but this last tank I'm back down to 10-11 mpg which is what I was getting before BB tune and intake.

We know why...

 

[Denali0229]

Lol, I've actually been trying to drive it nice and slow to get my mileage up but I live and work in downtown so its always stop and go. I gave up trying to save gas. It is what it is. It's easier to deal with when you accept your truck isn't made for being economical.