Missing butterfly plates from CMCV on intake manifold / how to clean?

[w4c66]

Making all kinds of discoveries as we pull apart the upper engine on my son's new (to him) '08 GT. After installing new plugs and coil packs the car threw a P2004 code. This car has 180k miles and the intake manifold and the butterfly plates are covered in carbon buildup. That of course may be contributing to the error code, but then I noticed two of the plates missing on bank 1 (cylinders 1 and 3). Just the plates are missing, not the hinged brackets.

I know there's been a 360 on the plate deletes for non-modified cars and we're keeping this thing stock so I rather not do a delete (the actuator is hopefully fine and it's just a combination of the crud and missing plates).

I'm assuming there's no easy way to get new plates on these two valves, so I guess I can either leave them as they are and get a tune to remove the code, or else if possible replace just that bank of valves instead of the whole manifold?

Also, I've seen all kinds of recommendations for cleaning these manifolds, but most of the cleaners I've seen used are corrosive to either the plastic/rubber (degreasers like brake cleaner, throttle body cleaner, etc) or corrosive to metal (purple power). The best might be seafoam and/or dawn dishwashing detergent?

 

[Dino Dino Bambino]

You basically have two choices. Either buy a good used intake manifold with CMCV assemblies attached, or delete the CMCVs from your existing manifold and get a CMCV delete custom tune. I deleted mine 8 years ago and haven't looked back.

 

[RED09GT]

On an 08, the plates holding the CMCV gear should be separate from the intake manifold. There should be plenty of sets of plates out there if you throw up a WTB ad.

I got rid of mine and with a tune from a decent tuner, I did not lose any perceivable fuel economy or low speed power. If I were you, I'd pull the rest of the gear out, epoxy the holes shut and get tuned for ditching them. One less mechanical part to fail.

For cleaning the manifold, dish soap and water is what I use. A bottle brush is a big help as well.

 

[w4c66]

We're going to be selling this car when my son goes off to college in August so I'll probably take the cheapest route and look for just the CMCV valves on the one bank. I had to get a new borescope, I'm afraid one or both those plates are down in the cylinder head on top of the valves but the car hasn't been acting like there's something down there.

With the cost of seafoam I think Dawn is the way we'll go to clean. I saw a video where a guy used a long brush to clean the manifold, I have long bendable aquarium brushes of varying widths that'd be perfect. Thanks for the inputs.

 

[Midlife Crises]

Dish washing liquid and hot water with a bottle brush will work fine for cleaning the oily goop out of the manifold and I am real curious where the missing plates are. What hardware went with them?

 

[beampro5]

I have the same issue

 

[w4c66]

Dish washing liquid and hot water with a bottle brush will work fine for cleaning the oily goop out of the manifold and I am real curious where the missing plates are. What hardware went with them?

UPDATE: Dawn and hot water worked well. Found one of the plates on top of the valves in the cylinder head, no signs of the other plate. Hope a prior owner found and removed it, no issues or errors for that cylinder as far as I can tell, and honestly I'm afraid to look =^0

Got everything back together and P2004 error is gone. Now getting a P2272 detecting the O2 sensor for bank 2 sensor 2 is stuck lean, but I think it's unrelated since it's from the other bank than the CMCV code. I guess it could be possible we screwed things up putting everything back together, but I'd think there'd be an error from the first O2 sensor if it was an air/fuel intake issue, vs an error from the cat?