Question regarding upgraded intakes

[DOCMORGY]

I was wondering what people's thoughts were regarding the upgraded air intake kits that are so popular with our Explorers. I purchased a K&N FIPK II kit for my 2001 Sport & intalled it...I noticed a DECREASE in power, worse mileage & periodic misfires (none of which I had in past). I removed the kit & this all subsided. My truck only has 32K miles on it & none of these symptoms ever recurred. I have since sold the kit. I also noticed that two vacuum lines to my stock airbox needed to be plugged with included plugs. Did this loss of vacuum affect my ignition advance & lead to poor performance (admittedly I'm guessing, I'm not a doctor of auto mechanics). I had also noticed the same type of poor gains with my '91 Navajo with both the *** kit & another off eBay kit. So, at this point I have left both trucks stock as far as airboxes. Anybody have any feedback or first-hand knowledge to share, since I'd like to improve on the stock airbox, but do not want the poor performance that I experienced with both trucks (both run excellent now). Thanks in advance.

 

[Nate1]

Did you reset your computer afterwards to adjust to the new airflow patterns? If your computer bases its mixture off of old data, you may burn rich or lean, causing poor performance and drops in milage.

 

[DOCMORGY]

Yah, left the battery unplugged for several hours to ensure that previous mode was deleted so that it could reset (did this on both trucks). I still think it has something to do with those vacuum hoses that are left unattached/plugged.

Also, I note that you have the Apten dual mode chip. I just installed mine & have really noticed a huge difference as far as shift firmness & a little better acceleration even on 87 mode. Just in the process of burning thru the rest of my 87 so I can switch over to 91. But, I also have a little crappier idle vs. before I installed it: have you had the same experience? Also, my mileage has dropped from 19 in mixed to 17, though it might be also that I'm putting my foot into it alot more now? How's your chip been treating you? And anyone else have an opinion as far as the airboxes go?