Carbon buildup on intake valves
 

I had my intake manifold off last weekend, and looking at the intake valves, they were covered in so much carbon. Why would that be? I thought these cars were meant to be quite clean with the direct and port injection system? I did have a pop tune on the car for a couple months at one point and never used again. Could that be?

Post a picture, hard to judge it without. Carbon buildup is still going to happen. Ever see a car that only has port injection? Still plenty of carbon buildup.

I never took a photo when I took the manifold off sadly. But this picture I found online literally looks like mine in terms of carbon buildup. Use this as reference. https://ibb.co/GpzL5fB

That looks like way too much.

Here is a 60k mile motor I am tearing down.

I would say this is on the heavy side of normal.

https://uploads.tapatalk-cdn.com/202...634357ab57.jpg

What would cause such abnormal heavy buildup

Blowby or bad pcv.

I had a compression test done on the engine a couple weeks ago. I got 215 and 210 psi on all 4. So I think blowby is out of question?

Likely not, but a leakdown would be the way to know for sure. It is getting oil from somewhere. What mods on the car? I know someone showed a way to clean the deposits but I can't remember. They dumped some cleaner into the PCV port on the intake manifold while it was running.

Oil can be be feed into the intake from the PCV or from another passage that comes up under the ac compressor and into the intake elbow. You might want to check those and see if there is a lot of sludge being pushed into the intake at those two points.

A clogged pcv maybe? I’ll have to look into it all for sure. Also, I run UEL headers, and a catback and that’s really about it. I’m thinking of installing a catch can asap. Very beneficial.

Hard to say. I would imagine a clogged PCV would manifest itself other ways. Catch can may be worth it for you.

Pcv hose into the air intake hose has a bit of oil shit on the end of it. Almost leaking into the air intake hose. Very sticky ew