It seems sometimes when I'm going 30-45 mph and give the truck a decent amount of gas, it has a big hesitation and isn't as quick to gain speed. Also, I noticed that occasionally when I start up my truck and go into drive or reverse and give it a little gas the truck gets jumpy where the RPM's will go up and down. Anyone have any ideas why this is happening or had this problem?

 

I test drove two FX4s back-to-back, one had an obvious throttle lag, the other had ZERO (or at least inperceptible) lag.

 

Does the FX4 have a different program than the 5.4 KR or 5.4 Lariat? If so what are the differences? If not why not just title this post 5.4 throttle response?

 

Had mine re-flashed on Monday after I mentioned to my dealer about throttle lag.

Took about 15-20 minutes. Since being done I guess I noticed a subtle difference. I'm hoping I'll notice a much bigger difference after I tune with the 1714.

 

Perhaps there's an issue with the amount of trans fluid in the trans? Could it be too low?

 

JTR, I had the exact same symptoms as you. They said the throttle lag was"normal" but they "updated PCM" for the "erratic idle". Got it back yesterday and so far(unless it's just in my head) it seems to have no lag.

 

Either a 1714 or an Xcalibrator will totally eliminate the throttle lag problem. I got one and what a difference. Instant throttle response and no hesitation whatsoever downshifting at any speed. It really made the truck fun to drive.

 

That throttle lag is in there so you can go rock crawling, at least that is what Fords lit (in the FX4 section). But I think that the lag was purposly put in the system by Ford so that when you mash it you put less stress on the drive line components. I need to get a tuner.

zman

 

Hmmm...Im due for a service and now that you mention it, I think I notice that too. Im going to have to turn mine in and ask them to reflash as well...

It usually happens when Im on the freeway and I want to accelerate to pass someone up...didnt think much of it until it was mentioned. Nothing serious, but I wouldnt mind having mine flashed.

What do I tell them?

 

Just tell the service manager that you're experiencing throttle lag and you would like them to re-flash it.

My service manager said no problem and did it.

 

I have a 2004 brochure and it says the following on page 17,

When the going gets tough

4-Low Electronic Throttle Control - Sometimes you really need to dig in. F-150's 4x4s incorporate a dedicated low-range calibration for maximum control of torque on rough surfaces.


It doesn't say anything about "throttle lag", "less stress on drive line components" or "rock crawling"...