2016 Mustang GT *Random Misfire's CEL* Charge Motion Valve "Flaps" in Intake Manifold

[TheNewOne]

Hello everyone,

So as the title states, I have random misfire CEL that comes and goes and the car runs fine but feels weird in the 1,000-2,000 RPM range. So gas mileage is obviously worse right now but the car runs and pulls just fine above 2,000 RPM.

After reading lots of posts on the internet I have it narrowed down to being the "flaps" in the Intake Manifold, which is stock.

I just called my local Ford dealer and they are saying the labor costs would be $1k+ to replace the "runner control something" which I assume is the Charge Motion Valve piece that is for sure cracked or broken.

What I am trying to figure out, is if this job should be cheaper if I buy the new version of the intake manifold (fr3z-9424-n) and do it myself or find someone willing to do it for less? Or just live with it until I decide to Supercharge the car...

Let me know if you have an insight on this issue or anything related to it.

Thank you!

 

[MustangIIMatt]

If it's causing misfires, "living with it" isn't a good idea because it will eventually lead to engine damage.

Find an independent shop that's competent of take it to the dealership.

 

[17P51GT]

Are there any mods under the hood?

 

[cvbm10]

I had the same issue on my 2017. turns out from the factory they forgot to put the clip inside a vacuum hose that sits right above the throttle body. so it was connected but not 100%. created random misfire code. dealer was saying it was the intake runner control module that opens n closes those flaps. turns out it was just missing the hose clip. did anyone diagnose this issue in person or just from browsing online?

 

[TheNewOne]

Are there any mods under the hood?

Yes, C & L Racer Cold Air Intake, X Pipe, 4” Catback Exhaust, BAMA Tuner with 91 octane race map.

I had the same issue on my 2017. turns out from the factory they forgot to put the clip inside a vacuum hose that sits right above the throttle body. so it was connected but not 100%. created random misfire code. dealer was saying it was the intake runner control module that opens n closes those flaps. turns out it was just missing the hose clip. did anyone diagnose this issue in person or just from browsing online?

Just browsing online. It has to be the runner control valves for me. I have 31,000 miles, owned the car since 1,000 miles, mostly highway easy driving. I’ve already got a quote from a local mechanic and he will do it for $740 with the new version of the intake manifold included.

 

[TheNewOne]

And it turns out I was completely right. Turns out the driver side control valve runner had snapped and was causing the flaps to stick in “flaps wide open mode” which caused the random misfires at low RPM.

Got the new updated version of the 15’-17’ intake manifold directly from Ford and had a certified mechanic install it and give me a 3 year warranty on the part and his work.

Paid almost $800 for the part and the labor which was more than half of what the dealer quoted me. I am happy now.