[rudeney]

What happens is that oil residue sucked into the manifold via the PCV system creates sludge that interferes with the movement of the flaps. This is what causes the actuators to break or for them not to return to their resting state. Replacing the manifold is the best solution.

 

[rudeney]

When I did the lever replacement on the ML350, there now way to do it without removing the manifold because the engine block lift ring was in the way. Even if that had not been the case, the kit I bought required some drilling and replacing plastic pins with bolts, ant there is now that could have been done with the manifold on the engine. Honestly, removing the manifold is not that big of a job, just get a new gasket.

Oh, and it may be a good idea to clean the inside of the manifold because that buildup is likely the cause of the lever breaking.

 

[rudeney]

So I changed the manifold with a brand new one.
solved all problems no DTCs showing.

interesting thing was the existing manifold appeared to be fine , I looked inside after I removed the throttle body . It appeared to be clean, no build up really.tumble flaps seemed to be intact no signs of degradation.

Interesting. Did you actually open it, or just look through the ports? I once saw one opened at it was VERY sludgy.

I also don’t think it’s possible to change the tumble flap laver cam by just removing the secondary air pump,
You can change it without pulling the entire manifold out if you lift the front of it up .
Also fuel rail doesn’t need to be removed either.

The problem is that most of the lever kits require some drilling, and you don't want to do that over the open intake ports. Once you get to where you can lift the manifold up like that, the few bits you'd need to get out of the way for full removal are minor. Yes, you would need to disconnect and unbolt the fuel rail, but by lifting it, you've already pulled it out of the injectors. I have just learned that sometimes, trying to save a few minutes of wrenching costs me more frustration later in the job.

Glad you got it fixed!