Aok2016

I guess you missed the part where he told you why. The parts that failed are non serviceable. thank Ford for that one.

Russell Shettle

All I want to know is the theory of operation.

The runners baffles are operated by vacuum. The vacuum to the diaphragm actuators is through electrical solenoids. I think that's what I learned from the video.

What controls the solenoids to apply vacuum and when? Is it the pressure sensor?

Are the runners opening and closing variably by changes in vacuum? I assume they close off flow when vacuum is high and open up fully on a WOT when vacuum is low.

Can anyone explain the theory of operation beyond what the individual components do?

N4HHE

I guess you did not understand my question. The parts were making noise but otherwise working. Not necessarily broken. Without a revised P/N it is going to happen again. And again. Why bother replacing? Based on replies this seems to be a common "failure".

Would understand replacing the part to mute the noise so as to get top dollar selling the truck.

N4HHE

Ditto.

OK, it is making noise, but nothing was said about why it was making noise and why the replacement manifold will not be making the same noise next week? Nothing was said about the noisy manifold affecting operation of the engine so one assumes performance was the same. So why bother changing the manifold?

Russell Shettle

I assumed that you couldn't replace or repair the components of the runner control components. What was making the noise was the lose connection to the vacuum actuators and the the runner valve plates were flapping to the air flow which I can imagine happening. I don't see why those components can't be replaced vs the whole manifold assembly. I wonder if it's just a loose set screw to the runner shaft. Without it all being in hand to asses, one can only speculate.

DrTriton

The PCM commands the solenoids on or off based on the control strategy in the calibration. In general, they are closed at idle/very low demand points in order to increase port velocity/intake charge motion. This promotes better air/fuel mixing, idle stability and reduces emissions.

When the electrical solenoids are commanded to open, they allow vacuum from a separate reservoir contained inside the intake to travel to the diaphrams and this causes the charge motion control valves to cycle to the closed or blocked position which allows air to flow through the intake restricted by the plates. At medium to high power demand levels port velocity is high enough that you don’t have fuel mixing issues so the charge motion valves aren’t required. The default mode is in the open, unrestricted position so that if the charge motion actuation system fails there will not be a power loss.

I suspect the charge motion plates are not cycling to a fully open or closed position on some of these intakes so what ends up happening is the air induction pulses cause them to rattle.

We assemble the Shelby GT350 version of this intake at my work, it has a different runner design for higher power output but the CMCV design is essentially a copy of what is on the trucks.

To answer the last question about replacement sub-components, the shaft and plate assemblies are molded in to the intake, they cannot be serviced as a separate end item without cutting the intake in half and rendering it unusable. Not my design, don’t shoot the messenger 😊

Russell Shettle

Thanks. I thought as much that the entire intake plenum was molded into one piece. So the runner flaps are closed at idle which gives a high airflow velocity, improving fuel mixing. Makes sense. I imagine it would stay closed until a demand for power when throttling up, rpm drawing in more air. Variable or fully open/closed.

DrTriton

They are either full open or full closed, they do not modulate to partial positions.

Stu Cazzo

Plastic parts...never thought i'd see the day where intake manifolds were made outta plastic!

Anyway...what this guy does(did) which is what no one else seems to do anymore is diagnose the problem, trouble shoot it and then using some good common sense approaches makes a final determination and then finds the necessary fix.

Seems that the dealers nowadays need a code so they can cross reference it in a manual and then make the designated fix associated with that code which pretty much removes all levels of thought process from the equation.

Anyway...good video!

DrTriton

Agreed - it’s very hard to find a good dealer tech who has the skill set to properly diagnose an issue these days. Part of the problem stems from the OE’s diagnostic pay rates, they just aren’t willing to compensate the dealers for all the time they often have to spend finding out what’s wrong. This forces them to use the code readers almost exclusively…if nothing shows up on the scanner then the customer ends up leaving without any resolution to the issue. That’s been my experience anyway…