I know that this subject has been covered before but would like to ask anyway. I have a 2004 f150 with 5.4 motor and 88,000+ miles. I am having the acceleration issue, not immediately but after the trucks been running for about 1/2 an hour. When I step on the gas pedal, it falls flat. Put the truck in neutral and it revs up no problem so it only does it when in gear. I changed the fuel filter in June when it first happened and it was fine till September. That turned out to be a module or some other gizmo that while I forget the name was a cheap and easy fix. Also at this time, I had the dreaded spark plugs changed but that's another story. Now it's November and it has happened again, took it to a shop last week and they changed the fuel filter saying it seemed to be plugged a bit. Took the truck for a long ride this weekend and it has happened again.


I guess I want some insight as to what it may be before I take it back to shop, I don't know what codes came up last time but if anyone has a few thoughts or opinions on this they would be greatly appreciated...

AT

 

Perhaps some clogged, stuck injectors? That can also lead to catalytic issues if not addressed, which results in hesitation. You should see if there are any pending codes. I'd also run some seafoam (or whichever additive you prefer) through the intake and gas tank.

 

what do you mean by "falls flat"? I have the exact same thing, but the symptom is about a second delay from when i hit my gas pedal to when it actually moves. it follows the exact same stipulations as yours (running for a while, delay, etc).

 

That actually sounds like the old TPS delay problem inherent to these trucks. Takes a programmer or reflash to resolve if that is indeed the issue. Any codes?

 

Yes, same as I was thinking. My truck would almost get me killed with the hesitation. Got it reflashed and that solved the problem. Then got a tuner, and that REALLY solved the problem.

 

hmm, thats weird. i just replaced my entire throttle body, including the tps, about 4 months ago.

reflash... i take it that's something different than just disconnecting the battery for a little bit? either way, im looking to get the new edge when it comes out for our trucks.

 

A reflash is a new computer tune from a dealer.

 

Ok, what is a tuner and how did that solve the problem? Also to get it reflashed, does that have to be done at a ford dealer?

Thanks

AT

 

Basically a "tuner" is a device (or person that writes a tune) that puts a new computer "tune" into your truck. This tune controls they way the drive train operates. It controls fuel flow, ignition timing, shift points and pressures, etc etc. At the end of the day, you get more HP/TQ, better throttle response and sometimes even improved MPGs (assuming you're not flooring it all the time).

"Canned tunes" are generic tunes written for a specific make and model, but that's as detailed as they get. These usually offer some increase in performance, but leave room for improvement. "Custom tunes" are tunes written specifically for your vehicle, and yours alone. The tuner takes into consideration not just the type of vehicle, but it's specific computer code (there are dozens of codes for just the 04-08 F-150's), any after market parts (exhaust, intake, headers, supercharger, etc), the location of the vehicle (a truck in Denver CO has very different ambient conditions than the same truck sitting in Miami FL, or Northern Manitoba, CA), age and condition of the vehicle, etc etc. You get a much more specific tune that yields higher performing vehicle.

Check out J&Js write up. Very good stuff here if you're just getting started: https://www.f150online.com/forums/ch...unes-read.html

While you're at it, there is more information there than you can shake a stick at here: Chips, Tuners & Programming

A dealer reflash is pretty much the same thing, only the new tune comes from Ford, not an aftermarket tuner. So yes, it needs to be done at the dealership. Thing is, you get Ford's tune, which is the most "average-joe" type tune. It may help with your problem, then again, it may not.

The big 3 as far as tunes go (around here at least) are Troyer Performance, VMP and now PHP. I don't think you'll go wrong with any of those places, but I can only personally speak for Troyer Performance. You'll wait a good while to get your tune, but it's well worth the wait.

- NCSU

 

Ok, I am still curious though, while I do not have the codes that the computer showed last week, I was told that they told the garage that there is a gas flow issue, hence checking the easiest thing first, the filter. What other things would cause this hesitation, not immediately after starting up but after about 1/2 an hour? Could it be the fuel pump or would that cause hesitation immediately? I just want to narrow down to the most likely causes if that is even possible without knowing the exact codes. Thanks...

AT