99 5.4 4x4 auto


Don't want to clog up the forums with some mumbo jumbo but something happened today on the trip home from the coast that I have never experienced before in any of the 3 5.4's I have owned. Maybe someone else has experienced this.

Was on about a 6% incline, over drive was off and was passing some cars doing about 70-75 or so. Rpm's were about 3200-3500ish and as the passing lanes were coming to a close I wanted to get past the problem truck that was jamming up traffic so I put it to the floor. No downshift at that speed/rpm but it was accelerating nicely. Started to approach 85 and out of nowhere the intake makes this loud droning noise and the truck starts to accelerate quicker (hence the v-tech title) lol. I was like wtf... so I let off a bit (had already passed the truck I was after) and the noise went away. So I floored it again and right around 80-85 the noise came back. It was a very distinctive loud drone coming from what seemed to be the intake. Was not an exhaust noise. No other weird issues, shifts or anything. Only way I can describe it is it seemed like v-tech. Sadly I have owned a honda SI and am familiar with the v-tech. Obviously I know it is not, but that was the best way to describe it. Anyone else ever experience that? First time for me, kinda stumped as to what it was.

 

Can't explain it either...other than a nice sweet spot for lack of a better description. but do have a few thoughts.

1st more questions;
In your prior (3) 5.4's...were they in trucks? were they the same set up? meaning all were 97-99' vintage and 4x4, same gear ratio, same tranny...etc. This would also mean if you had taken all 3 prior trucks on the same hill and tiring to pass @ the same speed and same load. Just tiring to replicate same scenario for all to get a even back ground to help see if & what was different for you.

do you know what kind of elevation you were at when this strange, but nice, performance was taking place? I have heard/ read that in areas where somewhat extreme elevation changes are ...there can be areas that happen to get extra Uupph in the upper ranges. I would think that to get this the air density & temp would need to be just so to get this to occur, but that don't explain the noise?

As for the noise....Maybe...and this is along shot... you got a experimental throttle body or intake that has "slipped through".

which leads me to more questions. Is the 99' a PI head engine or non PI? (Performance Inhanced)?? have you changed the engine or intake on this unit?

 

The first 5.4 was in a 98 exped (non PI). Then both 99 (PI's) in 4x4 trucks. All auto's. I was going over a pass, elevation was about 1500ft near the top where I was. Went from sea level to 1500ft in about 45 miles. I do have the gotts mod and a magnapack, other than that engine is stock. I've gone over that pass hundreds of times in the last few years and passed many cars. That is probably the hardest I have pushed the truck to make a pass though on that incline. First time I have felt/heard that happen.

Only thing I can think of is my cat's have been pinging on cool downs/shut off's (they are not glowing, I have checked) lately and they are original (140k). Maybe they are getting clogged up... and pushing the truck hard blew them out or something..but I would have heard that. I dunno. I have been meaning to change them as I have newer ones to swap in there, just no time. Truck is running great though and I would think if that was the case, it would be noticeable afterward. Which, it wasn't. Just those 2 times it happened, after that things seemed normal. Nect time I go over there, I'll bring a camera. Weirdest thing really.

 

what kind of RPMs are you looking at?

A resitriction in the exhaust could explain some things...generally... if this was the case the harder you press the RPMs would yeild very little difference if not worse. unless the torque wrap up creates a slight exhaust leak with consistant load of 6% grade, then once the leak hits, creates a "surge" of power?

It could also be on the other end...the throttle body. how clean is the throttle body and intake?? all the hose clamps tight?

hows the rear tranny mount?? engine mounts?

 

IDK what gearing you have, but my truck generally goes into 3rd gear at around 85-90MPH. Could you have just downshifted into second and thats why there was a noise? It would be doing higher RPMs so there is the noise, it would be high in the powerband, explaining the power.

 

IMRC

at 3000rpms they open up and allow the intake to breathe as much as it can

 

Didn't know that... learn something new everyday. I do have the metal intake and during my swap had removed the insulation on the lower plastic intake (fell apart from washing it). Guess that would make it louder. Just never imagined it being that distinctive of a noise change like that. I dig it

 

I was going to say... I have a tuner from VMP, but the same sound/thing happens right before I hit 3K rpms. Truck kicks it up a notch makes some deep grumbling sound and goes. Almost like the powerband on my old dirt bike when it kicked in.

 

here, i found a better description of how it works on a SHO forum

The air induction system improves engine performance by using the intake manifold runner control (IMRC) assemblies as follows:

The intake manifold has two runners per cylinder, feeding each of the intake parts in the cylinder heads. The IMRC assemblies are located between the intake manifold and cylinder heads, providing two air passages for each cylinder.

One air passage is always open and the other passage switches from closed to open by means of a valve plate. Below 3000 rpm, this valve plate is closed to improve low-speed and cold engine performance. Above 3000 rpm, this valve plate opens to improve high-speed engine performance. This is what you hear as your car hits 3400 rpm's; the "secondaries" open up. If you can't hear this on your car, and your SHO seems a bit slower or sluggish, your IMRC deactivation motor may be damaged. It will need to be replaced to bring the SHO back up to speed again.

The valve plates are opened and closed by the IMRC deactivation motor, which is controlled by the powertrain control module (PCM)

 

https://www.f150online.com/forums/ge...-pants-11.html

 

Almost forgot about that thread

 

The imrc's are found on 4v engines not 2v, hence in the SHO. My guess is that you felt a down shift or the torque converter unlocked.

 

Damn it. So I don't have v-tech. What am I going to tell my friends now.

J/K

I was going to say, I remember having my intake plenum off and cleaning it, never saw 2 runners on each cylinder, just one. Plus I have been trying to get it to make that sound again and can't.


Wasn't a downshift and shouldn't have been the TC unlocking as I was already pretty heavy footed into the 6% climb passing cars at about 75ish when I put it all the way to the floor to try and get the last guy. No downshifts at that point, just picked up speed and right around 85 or so and foot still to the floor is when I heard/felt it. Just a loud drone appeared from what seemed like the intake area and a slight increase in power it seemed. Maybe something stuck and finally broke loose under heavy load, I dunno.

 

do you have something to prove this? i've read on wiki and other sites that the 4v has them, but i would figure all mod motors have it. took apart a 3v 4.6 that has them.

 

From what I am finding, the 4.2L v6 has a IMRC, along with ford rangers, mustangs etc... can't find anything on a 2v SOHC 5.4L though