K&N+ Drilled airbox=lower mpg

[Houston at NCSU]

I just installed my K&N and drilled my airbox last weekend, however, my gas milage has dropped through the floor. I have gone from around 15 in town, to 11 or 12. My vacuum lines, and MAF are both hooked up correctly, anyone have any ideas on what is wrong?

 

[jimbo74]

did you forget to reset the computer. using the stock settings wit hthose mods will actually lose mpg....dont know how to reset it? diconnect the negative for 10-20 minutes...reconnect it then start it up..

 

[Houston at NCSU]

Thanks, I have not done that yet, so far the mods seemed to have improved acceleration, and if I can improve my gas milage i would be really satisfied with it.

 

[jimbo74]

NOT SURE ABOUT IMPROVING IT BUT KEEPING IT ABOUT THE SAME, JUST WITH MORE ON TAP POWER

 

[Alec]

Yup, the fact that you didn't reset the computer is the problem. Like James said, disconnect the negative battery lead for about 15 minutes. When you reconnect it and start the truck back up, let it idle for about 10 minutes with all accessories off. If it's really cold outside, let it idle for 20 or more (the engine should be good and warm for the computer to relearn).

You should see an even better performance gain and about 1 mpg better than you had stock.

 

[wabbit]

might be the "lead-foot test-mode"...

Any time I have done something to the engine, intake, or exhaust, my initial mpg decreases. That is because I go zippin' around, tryin' to pop wheelies to test and see if performance has improved. Thus, sucking more gas.
Resetting the computer is essential (as described). Also, if your looking for performance, when you first take a drive, run the motor more aggressively. This will establish a profile in the computer that is optimum for performance.