I have a 2007 I bought about six months ago and just turned 20k miles on it. I just installed a K&N air intake system and noticed my mileage went down just over .5 miles to the gallon. I was not expecting this great increase if any in mileage, however I was not expecting such a decrease. Installation I believe is to the book I checked in over about 5 times.

Please provide some advice how to get my mileage back, like a bone head I already threw away my stock intake (I know dumb, but never had this problem with any of my cars before). I have heard the engine breaths cooler with these on and tricks the computer in running the mixture richer due to the cooler temp. Not sure if that's true though. Should I put in a chip? Any information or solutions would be greatly appreciated. I am paying a small fortune in gas as it is. Thanks.

 

Welcome to the forum...
If GM could get .5 more mpg from an air intake and filter change they probably would have already put that option in...honestly the K&N filter and intake are a gimmick, there are many other things that would need to be changed to get better engine performance and most, if not all, DO NOT include better MPG...
(step down from soap box)
In all likely hood the filter and intake have made little to no change, what has likely happen is your driving habits have changed since the upgrade...
try driving a little lighter in the foot and keeping the RPM's under 2k and you will get that .5 back....

 

Also are you going by the DIC mpg readings or actual calculations?



Over oiling the filter can coke the MAF which will cause problems. The OEM is a CAI w/ intake noise reduction resonance chambers built in. Since the ECM monitors the air temp, any change will be compensated for by the ECM.

As in2pro said, these aftermarket gizmos are about as useful as TBI spacers and other add-ons. Is the K&N CAI sealed from the underhood air? If not, then that could be your problem.

I tried the GM Performance CAI on my 2007. About all I noticed was the increased induction noise @ WOT which induces more WOT excursions.

 

I never understood why anyone would buy one of those. K&N used to advertise that you save money because you never buy another filter, while ignoring that you have to buy the filter cleaning kit and do the work of cleaning the filter.