2004 f150 lariat 5.4 auto 4x4 @75k crew


oki so im getting really tired of my truck i took a drive out to denver this weekend(approx. 245miles) and i made it no problem but i was heading back home tonight and i had my cruise control on and when it downshifted to go up a hill the truck started buckling. as if it was redlining but it was at around 3500rpm. if i just eased on it then it would drive fine. but as soon as it actually downshifted it would start doing it again. no check engine light no nothing. someone please tell me they know whats going on!

i took this truck to texas earlier this year and it did it to me in houston about 1400miles into my drive i immediatly pulled over and dropped it off at a dealer. they checked it and said my fuel system was all messed up and my transmission was about to break down and quoted me 1800 dollars to fix. i told them i couldn't do it so i went to pick it up. i pulled out from the dealer and it drove perfect. i took it to a regular shop to have the trans serviced and they said i should just wait another 30k before i service it. so someone please help me i really dont want to take it to a dealer again!!

 

sounds like a missfire or 2. possibly a drop in fuel pressure under load. when was the last time you changed the fuel filter? thats where i would start if your going to try this yourself. be very carefull with the fuel filter clip. if you dont know how to remove it bring it to someone who does or you will break it.

 

At 75k you should have let them service the tranny if it's never been done. Concur with the fuel filter recommendation.

You may want to get new spark plugs if those are originals, but do some reading here about the issues.

 

Have you tried putting some drygas in? It seems this only happens on long trips, right? Maybe the change in climates and elevations, or the process of getting your truck really hot on long trips and then cooling overnight, is introducing moisture into the gas tank through condensation.

I mainly suggest this because we had this same problem on my Dad's motorhome (with a Ford V10 gas engine). It would run really rough and even stall at stoplights and do the same shutter thing you describe. We determined that it was due to running the generator which warmed things up under the back of the motorhome and then as it cooled there was condensation (conclusion was backed by the fact that the problem only happened after being at Brickyard all weekend, several years in a row... the only time the generator sees extended usage).

So try some dry-gas. And change the filter too, it never hurts.

 

well like i said i took the truck to get the tranny serviced and they said it the oil seemed to be brand new and that i should just wait to service it and i bought the truck with 60k on it and the dealership said they did service the tranny when i bought it.

and the fuel filter hasn't been changed by me atleast. but the last dealership i took it to mentioned that clip being broke and honestly im pretty sure they are the ones that broke it.

and yes this only happens on long trips. last time it happened i had driven for 22 hours straight. and this time well i had drove 250 miles one way and i was about160 miles coming back, as long as i didnt push it the truck ran great.


are there any write ups on changing the fuel filter?? regadless thanks for the help guys i really appreciate it!!

btw the last dealership where i took it said that it was a drop in fuel pressure under load

 

Yep... there are tons of posts about it...
I'm particularly partial to my own reply in this thread
https://www.f150online.com/forums/sh...Filter+Removal

Mine is towards the bottom of that page.

If you have time, read through the entire post. But the main thing to read is that you do not have to remove the entire clip to pull the line off. Just slide the tool in and the line will come off.

And if you already have a broken clip, make sure you buy a filter that comes with clips. Or just buy the clips from Ford.

This posting also has some nice pictures and a writeup. But unfortunately he tells you to remove the clips entirely, which is unnecessary and greatly increases the chances of breaking the clips
https://www.f150online.com/forums/sh...ht=fuel+filter

Good luck... hopefully this fixes your problem!

 

thanks im about to look into it right now. also i went and purchased some heet they dont have any drygas around here. i took it for a test drive and now it doesn't do it when downshifting but it does still do it at WOT. any thoughts?

 

If i understand what you are saying, then this should help you:

Normal function of the PCM. You force a downshift because of pedal position, you let off but the truck as still downshifted. Because of TQ. management it will hold a RPM speed untill the upshift is complete. And thats where you get the redline/hanging of the RPMs.

 

replace the fuel filter. if the fuel pressure still drops under WOT you need a fuel pump. dont worry about the trans untill the engine is operating correctly. a poorly running engine can mimick tranny issues.

 

thanks everyone for their help i am going to be working on this till tomorrow i've been out of town worrying about this thing for almost two weeks now lol so ill let you guys know what happens

im not too worried about the tranny like i said it shifts perfect. i just hope its the fuel filter=(

 

well i just wanted to let everyone know that i changed my fuel filter today and so far my truck is driving perfect. I am praying to God that this fixes it. i left my job today and ill be driving 1500 miles home tomorrow so that'll be the test of faith! thanks!!

 

You have a 1500 mile commute?!?!?

 

sounds like the tranny is getting hot, and needs a flush

 

Yes just dont spill it all over yourself and youll be good
It's hot and tingles a little bit. Make sure you run your truck for a bit then re-check your levels

 

lol oh no! not a 1500 mile commute i just been working here in wyoming for way too long. its time to go home.


on another note i put about 100miles on the truck and it started doing it again. i started just pumping 10 dollars into it since it seemed to do it more when i was low on gas. it drove perfect so i went ahead and filled it up last night and it started again. the only difference is that this time it gave me a check engine light. i went and checked and it said the "fuel rail pressure sensor". the ppl at the automotive store said i must have a bad tank of gas. they also said that the gas station i pumped at was known around here for having bad gas. i found it hard to believe since it was a shell and i pump nothing but 91octane. so they sold me some HEET and said that i should wait till i fill up again and then see if it keeps on. so if anyone can shed any light on this please help me im running out of ideas!!


and for the ppl that said the tranny, well i guess that could be a possiblity but i have had the tranny checked and with the recent check engine light and the fact that when i changed the filter it drove good i'm more leaning towards a fuel problem. do you agree? or is the tranny heating up a common problem in these trucks? let me know thanks everyone for their help!