I took the intake manifold off of my friends beta last weekend and discovered an oily crud buildup in intake ports of the manifold runners. I've never seen this before, and mine looked spotless by comparison when I removed it. The buildup was on cylinders 1-3 only. Number 2 and 4 were clean.

 

Blowby that gets cooked by the heat. It come from the PCV system and is caused by leakage past the piston rings. You can use a catch can in line of the PCV valve to intake manifold to collect the blowby gases and dump them manually. You can also use some Auto-RX in the oil to clean the rings so they seal better. The Auto-RX is a long term solution and takes a few thousand mile to be completely effective.

 

Or spray seafoam in the intake manifold. Let it sit for a few minutes, then fire it up and watch the white smoke for a few minutes.

 

^^ That will clean it out but not cure the problem.

 

^^ Definitely agree. It just helps get rid of all the crud that's been building up in there to get you a clean start.



Kinda odd that it was only half the cylinders that had stuff building up in it. Kinda makes me wonder if a seal has gone bad or something.

 

What's the FI setup like? Usually if the FI is spraying directly into the port it keeps it clean.