What causes this? What I don't understand is how this carbon (which is just burnt fuel, correct?) gets all in the intake. I mean, only air gets in there right? Or does the EGR let a bunch of fuel in there and that's what causes this carbon build up? Man, I took apart my intake today and there is gobs of carbon buildup in the upper, lower and runners.

I just don't think this is normal. There must be something causing this. Also, I can really smell fuel in there, even though the car has been sitting for awhile. I wonder if my injectors are leaking? I'm going to be sending those off to be cleaned, so hopefully that will help. But how else does so much gas and carbon crap get in the intake?

Also, put brand new plugs in and after just letting the car idle for a little bit, the plugs are already turning black with carbon crap on them. Man, what's going on here?

Any help on this would be appreciated.

 

Check out your PVC valve, Oil/combustion gasses also pass through the plenum, runners and intake. That has probably accounted for a good portion of the build up. I believe that it is fairly common to have deposits in there, as I have them, and someone else I know with TPI had them...

Anyone else care to charm in? I'm curious if it is common to have the deposits.

 

Totally normal - almost impossible to avoid.

It is from the PCV system I believe... I tried to find the exact explanation in the book where I read it, but failed to find it.

I have heard that sea foam works well to get rid of it.

 

ok i've heard nothing but good things from seafoam but i'm curious on how you use it to clean your intake

from what i heard do you just unhook a vaccum line and let it get sucked up in it or what i'm confused

 

Is your engine stock? An aggressive cam can sometimes allow the air/fuel mixture to reverse flow back into the intake during overlap, and this can cause buildup. This doesnt explain the buildup on the plugs, though. The black plugs could be due to a rich condition as well. Does the car smoke at all?

 

Nope, car don't smoke. But I'm pretty sure the car does run pretty rich because it will actually start burning your eyes by just standing next to the car while it idles.

 

You allow 2/3 of one bottle to be combusted via vaccuum line, and pour the remaining 1/3 into the crankcase. You also add a bottle (all of it) to the gas tank.

I have heard lots of good stuff too. In order to use the vaccuum line, you feed it two or three seconds at a time, and then right before you are ready to pour into the crankcase you allow it stall out with vaccuum line immersed in seafoam. It stalls, you rehook up line and pour rest of contents into crankcase, and add the bottle to the gas tank. Drive hard for the whole tank, and make sure to bring up to full sing on the highway for an extended period of time. That's how its done.