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OK, I have my 3.5 tore down. Can someone explain the reasoning for the intake manifold/plenum setup. There are 6 throttle plates inside the plenum that are vacumn activated. Is this basically working like a vacumn secondary on a carb?


The intake is a dual-runner design. Long runners at low rpm for improved torque, then they switch over to short runners at higher rpm for improved breathing and hp.

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Is there a drawback to removing them?


Yes. You will loose either torque at low rpm, or hp at high rpm, depending on what runners are "on" with the plates removed.


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I noticed that there is a lso alot of carbon buildup on the inside of the plenum, back on the TB and on the plates. It is causing it to stick. Any suggestions?
Thanks,


Clean it out? There's not really anything you can do to prevent it. Carbon build-up is just something all engines have with EGR and PCV system. Not much you can do without disabling these.

--Dan