F-1Fizzy

btw...just brought truck to stock tune and if anything it actually got worse then it was before...ugh...this is annoying...lol...idle drops to like 360 or so and gets rough whenever i come to a stop now then jumps back up to around 450-550 or so....then stays normal....but everytime i stop it dips down to 350 or so and then goes up and stays normal once....

stevens_05

Fizzy I am having the exact same problem with my truck and without the program mine gets worst also. It is also a 2004 fx4 and mine has been doing it bad for about a month. If possible can u keep me posted on what u find out. mine does it everytime i come 2 a stop and it will just up and die on me. Thanks

sigar150

Borrowed this from TOS to help you identify the IAC, easiest to replace it and costs anywhere from $60.00 to $90.00

Idle Air Control Valve

The idle air control (IAC) valve assembly controls engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine rpm and increases or decreases the IAC duty cycle in order to achieve the desired rpm. The IAC valve [is also] part of the throttle body assembly...

The PCM uses the IAC valve assembly to control:

- No touch start

- Cold engine fast idle for rapid warm-up

- Idle (corrects for engine load)

- Stumble or stalling on deceleration (provides a dashpot function)

- Over-temperature idle boost.

And here is a nice diagram of a typical IAC:
Attached Images

seniorFORDtech

Please correct me if I'm wrong but the 5.4 does not have a IAC motor It is pcm controlled through tp sensors on the T/B I would remove the T/B and clean the sludge off the T/B and plates, also remove your mass air flow sensor and clean the hot wire on the inside of the maf
disconnect the battery prior to this, as this will clear KEEP ALIVE MEMORYand relearn adaptive strategy you will need to drive the truck over 30mph for approx 1 mile to relearn strategy.. good luck

sigar150

I just went and looked at my truck, My wife's 03 with the 5.4 has one ( I definately knew that because I had to change it out for it's rough idle issue) but my 06 with the 5.4 does not. I connot say I'm sure about the 04, they may have made that change in 04.

seniorFORDtech

Heritage model will have an IAC the new 04 body will not..
if you have a heritage the problem is either a iac or more so a vacccum leak of your pcv tube going to the intake manifold there is a 90 degree elbow in the back of the motor follow the pcv line from the pcv valve you will see it look closely at that elbow it may be sucked in or open causing a vacumm leak..

token

Another possibility is a clogged cat.

Do you have a wideband Air/Fuel guage installed in your truck. I found this necessary, especially after being tuned. Some tunes are set a little on the rich side to begin with.

Weather changes can throw your A/F ratio out of whack, causing you to run pig rich, and clog up a cat pretty quickly.

Clogged cat = too much back pressure. So stalling @ idle is then common.

F-1Fizzy

i have the new body style 04

F-1Fizzy

i have the edge programmer for the truck....does that have the air/fuel ratio gauge you are referring to?...the truck has def been better recently but it does run much better with the tune then w/o it...