Ok folks, Im new here, Ive got a 2001 F150 4x4 lariat 5.4 engine,K&N single catback exhause..I think gibson makes it??? this truck runs wicked in the winter cooler air, but runs sluggish in the summer, or when the outside air is above 65F no bottom in, Ive installed a K&N fipk generation II kit, and its worse, in summer but runs awesome in winter, so I went back to stock air box setup..the truck is stock except for the exhaust and has 70,000 miles and Ive had this problem since new, I replaced the mass air senser, and have had 2 differerant ford dealer ships look at it, its never set any codes and idles good and normal in cooler weather runs good..Its like the ford is very heat tempermental, Im wanting to re install the K&N FIPK kit but theres no heat guard , when I called K&N and explained the problem they said the ford was,nt temperture sensitive so thats why there no heat sheild..i find it to be oppisite, anyone experiance this problem, I love my truck..and Im wanting to install bigger tires and 2" lift kit, I just want it right..its like im looseing torque..thanks in advance..

 

hot air from under the hood is not a good performance thing on ANY motor. the stock box gets the cool air from inside the fender, behind the head light. the K&N gets hot air after it has run thru a 200 degree radiator. thats a big difference.

 

Thanks steve..Yes I agree, But even with the stock box on in the summer I can feel a sluggish bottom end differance, Im thinking maybe a sensor is bad, But it keeps stumping the dealerships and mechanics..truck runs awesome in cooler weather..the warmer air affect the 5.4 with stock air box, and its worse with the K&N air kit, thats why I went back to stock air box setup..should ambiant temps affect performance..the truck is geared 3:55..its a extended cab 4x4 lariat..Its just driveing me nuts as to what would caus bad performance in summer month, right now the temps here in NC are in the 40F and I can light up the street..in summer temps 60 to 65F push gas and it acts like its not getting enough gas running to lean..no power till I get rpms up..anyone have any Ideas...

 

My truck makes way more HP in the winter. Loves the cold air.All motors do!
+ in the cold the tires will spin essayer. The cold temp makes the rubber harder so they spin essayer.
If your going with bigger tires you should put a set of higher gears in it.
I run 4.10s in my truck and love it.
Also, a tuner may help a little.

 

Thanks phill, i also have a 1997 4.6 expedition completely stock and i cant tell any change in running between winter or summer it always runs great..On the other hand my 5.4 in my 2001 pickup is a dog in the summer time, Ive heard that the 5.4 triton needs more back pressure and im wondering if the K&N single catback exhaust is killing its performance it warmer months..Is it possible, i bought the truck and instantly changed the exhaust to bigger so i dont know what stock power is..All i know is when its cooler say around 40ish or lower man this truck comes to life in a hurry, and its even better with the FIPK kit..i see that K&N is now selling the 57 series with a heat sheild, i think i might try to get the sheild since mine did,nt come with 3 years ago when I purchased it..i dont know me and everyone else is stumped, I guess this summer, ill try and get some fuel pressure reading....since no codes are showing up..Its like the torque is zapped out, its gotta be a heat related problem, or throttle air fuel mixture, but whats changeing it, any pro;s out there got any ideas..the local dealersships are stumped, all they say is yep to be a 5.4 it should have more pick up when stabbing the gas..f course its winter now and its running great, just trying to get it fixed before summer...????

 

I don't know but it's not the exhaust. I had true duals put on my truck and did not notice any difference. The stock cats give you plenty of back presser.
Whens the last time you put a new fuel filter in it?

 

GO TO the top bar and click on TSB full discription and plug in the numbers 02-12-3.
Then click on the number again to get the full text information.
Print it out and take it to your dealer.
I know they have the same info but not to aggressive on helping you unless you push a little.
Good luck.

 

if you look at the K&N setup on the 5.4L, the open box design gets the air from the fender.....well, the Series 77 does.

 

Thanks for the input..Im running totally stock except for the single K&N catback exhaust that sounds sweeet..sounds like duels..Speaking of which I spoke to K&N tech service and they are sending me a new upgraded heat shield with a new filter for my genII FIPK kit free,cant beat that for customer service I bought the kit new back in 01 and explained to them my problems Ive had with the truck in warmer weather, and they said with the Filter kit and the tuned K&N exhaust which is no longer sold,It was expensive..the horsepower gains and punch should be impressive..and something was wrong and to try the new setup and give them a call with the results..I was very inpressed with there customer service..I have the series 57 the older one..big cone that sucks from around the fender..Blue grass-7 i;ll research the post thanks..
Ive changed out the fuel filter not to long ago..I keep my toys well maintained..i dont drive my truck much, I have a F550 company service work truck I tool around in..My F150 is a weekend warrior..I also have a superchip micro tunnerII
I will retry as well..Its set to stock for now..

 

Did you look at the TSB I referred you to for a 5.4 motor?

 

Thanks Bluegrass, I just checked it out, wow loads of info, The local dealership told me about the sluggish 100F ambiat temp ..so he reprogramed for it,did,nt make a difference but he said nothing about the body plugs..errrr, so I;ll check that and get some plugs if needed.. I also found 3 more tsb that relate to my trucks habbits,,

 

could be an 02 sensor giving an improper reading too.

 

you might try cleaning the mass airflow sensor and throttle body

oil from the k&n filter can cause problems

 

If you ask me it is normal, mine loves 50-65*F anything more and it just isn't as peppy. My outside temp sensor for my mirror is right in the inlet where the silencer mounts for the air intake, when it is above about 80* the under hood temp gets well into the low to mid 100's fairly quickly when in town. When the ambient temp is under 70* it rarely gets over 90*. I've even got a functional ram air hood, but if I am not moving very fast it doesn't make a difference.

 

Back when I posted this I was running stock tune with the superchip, and 87 octane only, and like galaxie posted the truck acted like it dont like warmer weather, I had an older K&N 57 series FIPK with no heat shield, since then I have Bumped the tuner up to performance tune and run only 93 octane and had K&N send me a new FIPK kit with heat sheild, WOW what a change in performance, the truck runs much better and seems to be not as sensitive, But Im sure once the temps get below 60 It will even run better..not sure why the octane would make a difference, But to me with the superchip on performance mode and the better octane its like a new truck..

I did the TSB mods my self..