Right, but the 4.2 is not a mod motor. The 4.6s, but not the 5.4s, have a tuning valve in the lower plenum that does work like imrc's.

 

once i manually pulled my truck to 2nd gear at 80MPH the RPM's shot up to 5,600 and bounced the rev limiter 3 times before i shifted back into drive.

the OP said it did not down shift.

ive noticed this with my 4.6L 2V kinda falls on its face in the first part of 3rd but once it gets a few more MPH it takes off.

is that tuning valve the big plasticy thing under the intake?? if so my buddys 97 expy 5.4L SOHC had that on there. thats what turns the intake from a 180* to 360* intake isnt it?

 

Here is a pic of the actual device removed and tied out of the way during JMC's 4.6 to 5.4 swap. https://www.f150online.com/forums/me...42-112397.html

All 97-00 and some 2001 4.6 engines use some sort of intake manifold runner control valve. Remove it from the 4.6 and plug it into the 4.6 harness and bolt it to the engine some where out of the way. Note; you can get a tune to remove its function and eliminate it all together. - JMC
https://www.f150online.com/forums/ar...wap-notes.html

It mounts on the front of lower plenum (big plastic thing) under the manifold. At low load/rpms it is closed to make the intake system act as a "short runner" intake, and opens at higher load/rpms to act as a "long runner" intake. It is simply a PCM controlled butterfly. You can see it back in there with a light and good eye.

 

so they have a imrc then? this is confusing......

 

No Yea it is confusing. Hang on, I'll post a diag.

 

This is The 5.4L, if that's what your referring to, I'm not far from confused either lol.

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ok, so they do have it! its just not called imrc.
regardless its a part of the intake manifold that opens up "flappers" (as old timers would call them) at a certain rpm point.

 

yeah mine doesnt have the thing next to the intake i dont think. but the plastic thign under the manifold has been there on every mod motor ive ever seen. 97 5.4 expy 2 of them my 97 4.6 my buddys 98 4.6L even his dads 2000 V10 had that thing.

i notice when im driving if i acc. slowly once i get past 2,800RPMS the truck seems to just want to take off no matter what the speed

 

If this is what you call a "flapper" -



That installs into the lower and what it looks like when pulled out.

 

the valve it opens is what i'm calling a "flapper"

 

I'm confused too! I thought that Intake Manifold Tuning Valve was on 4.6s only, and that is why JMC deleted it when he did the 5.4 swap.

 

I have a spare 00 ( 1 piece composite) intake manifold sitting right here, don't see anything like that. Unless it is on the inside..? I dunno. Maybe they were only the the 97-99 with metal intakes and a separate lower manifold?

 

Yea "flap (or flapper)" signifies a butterfly valve set up. Different deal than the set up I'm referring to - and what the pics point out.

It's a simple rotary valve design, - which is a much better than the butterfly set ups IMO.

All it is, -is what's pictured. She just a spinner, when need be.

 

Nope.

I'm not sure when the 4sixes got them.. (?). The 5fours had them since 97.

 

Yea, the 97 4.6L's have the same set ups -