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Discussion Starter · #1 ·
OK, I just installed a K&N FIPK on my wife's 05 silverado 1500 (5300 V8), expecting to get some more power as well as better mileage. (My 06 Mustang GT picked up about 2 mpg after a Cold Air system.) I have noticed a jump in the power, but the mileage seems to have dropped off considerably.

Previous mileage was about 17 MPG around town with some freeway driving. Mileage from the last tank was only about 12.5 MPG. Has anyone else had this problem?? Is there any sort of easy or cheap fix?

The truck has no other mods, has about 19K miles on it and is still under warranty. Any ideas are welcomed.

Please help!!
 

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Doesn't make any sense to me. I just installed the same thing on my '05, but I haven't driven it long enough to test the mpg. I can't think of any reason mileage would go down, unless maybe the right foot got a little heavier with the power increase? :rofl:
 

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I put the K&N replacement filter on my '04, but didn't see any improvement. I've heard of problems with excess oil on the mass air .... w/K&N filters. If it was new, it shouldn't have excess oil though.
 

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I put the K&N replacement filter on my '04, but didn't see any improvement. I've heard of problems with excess oil on the mass air .... w/K&N filters. If it was new, it shouldn't have excess oil though.
Usually if the mass air is getting oiled the check engine light will come on
 

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yea ive never heard of that especially that dramatic of a drop.... maybe something else happened at about the same time? a bad sensor of sorts?
 

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could be so many things, she could have been driving more town miles, driving with a heavier foot, bad gas(in the tank) etc, i would suggest you drive it a couple of tanks with the same miles on each tank and same driving style.
 

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Discussion Starter · #7 ·
The only driving style that differed is that I was driving it a little bit more to "test out the power gain." So that may have had something to do with the drop in mileage. I am not driving it for a couple of tanks so it is just one driving style over the same roads.
 

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i saw the biggest difference in upper RPM when passing, it was easier and a bit quicker to pick up speed
 

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Just an idea, would the computer be trying to keep up the richness with the incresed airflow from the K&N?..just an idea...
 

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I installed the K&N FIPK on my Wife's 2001 Suburban and there was a definite gain in power (esp. low-end) and the mileage seemed to improve (as long as my wife keeps her lead foot out of it) but i have never heard of a drop in mileage. I put the kit on around 25K miles and she has about 110K on it now and I have cleaned and re-oiled the filter several times without any problems with the MAF sensor. What octane fuel are you running? Ours runs best on 89 and will ping a bit when running anything lower.
 

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not to insult your intelligence but make sure your mass air sensor is connected, I already had an fipk on my 04 5.3 and when I installed my headers, I forgot to connect it. It didn't give me a light but it ran crappy. Another thing is something I learned from GM Hightech Performance is to take out the screen in the MAF, that might help.
 
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