Ouch. I guess the brass wire brush I used to clean the blades wasn't a good idea either. I was gentle but the stuff wasn't coming off very easily.

Any ideas why I seem to be experiencing more carbon buildup than before?

 

The PCV air supply line will flow backwards due to excessive blowby, and dump oil mist into the top of the throttle body. The oil drips out of the hole right in front of the throttle blades, and gets pulled through the throttle blades and through the IAC air hole.

Check the line from the passenger side valve cover to the throttle body for oil. Take the top plate off the throttle body and look for oil.

 

I will do that tomorrow morning and post what I find. Thanks for the lead.

 

I removed the inspection cover and the CCV hose on the passenger side and found signs of oil in both. It was starting to build up the black residue. I use throttle body cleaner and also fogged the intake plenum using the new Sea Foam spray can. This is a cool improvement to the liquid form because it allows you to inject a spray in front of the throttle plates while the engine is running to fully disperse the cleaner inside the plenum.

So it looks like I am suffering from excessive blow by as you suggested.

I have been researching the oil catch cans and vents, etc. I live in NJ with strict emissions requirements so I need to make sure whatever fix I use is legal for emissions testing.

I should also mention that this seems to be the cause of an oil leak I have been having. While inspecting the PCV valve, I noticed oil is pushing out around the PCV valve grommet and running back along the manifold and down the bell housing.

It appears I should install an oil separator catch can inline with the U shaped PCV hose. If it matters, I have the Edelbrock LT1 airgap intake manifold. Should I do anything on the CCV vent line? It seems the catch can will filter out the oil but it won't do anything to relieve the pressure that is causing the oil leak. Should I remove the CCV hose and install a vent filter on the valve cover and cap off the fitting on the throttle body? Not sure if that will pass emissions.

 

First make sure your PCV valve is working. If that's plugged up, it would explain the pressure building up in the crankcase, and blowing oil into the throttle body. As far a keeping the oil out of the throttle body, some people have use a small right angle filter made by Deutsch to replace the plastic elbow at the valve cover grommet. Seems like that would only help in mild cases, since a heavy oil flow would just seem to plug it up.

What you can get away with at inspection depends how close they look. Have they been popping the hood? In all the cars I've ever taken through NJ state-run stations, they have never popped the hood (excludes my Formula, which doesn't go to state-run stations). The breather would be a dead giveaway that you no longer have a closed PCV system. But how many of the people in the inspection station would even think of that? You could always just put the vent hose back on briefly for inspection.

 

You are right in that they don't usually pop the hood and I can put it back to stock for inspection. I failed for emissions (HC at idle, 340 versus 220 limit) this year for the first time and replaced the plugs and cleaned the air filter to pass. I wonder if this issue was part of that too.

I'll check the PCV valve and install the Deutsch filter elbow and catch can. Is the PCV system a closed system? In other words, will I need a vent to the outside to relieve the pressure if the PCV valve turns out to not be the cause of the pressure buildup problem?

 

An update - I installed the Deutsch vent filter on the passenger side and a new PCV valve. The old one was working but I replaced it anyway. I noticed quite a bit of sludge buildup on the inside of the PCV grommet. I never experienced this before the rebuild. Besides the mods list below, the only thing I am doing differently since the rebuild is I switched from dino oil (every 3,000 miles) to sythetic every 5,000 miles.

I am considering switching back to dino oil. What else could cause the sludge buildup? Could the blow by cause this?

 

Blowby is the products of combustion. One of the main products of combustion is water. The water is going to condense on the coolest parts of the system, and the valve covers cool down fast. That's why you usually the brown oil/water emulsion in the fill pipe, the vent, etc. Wouldn't have anything to do with synthetic vs. conventional oil.

Yes... PCV system is "closed".

 

Thanks Fred. I am going to go back to oil changes every 3,000 miles and stay with the synthetic for now to see if the problem reduces. I never saw any build up of sludge before the rebuild so I am attributing this and the IAC port/pintle problem to the combustion byproducts from blowby due to the new engine config and the extension of the oil change interval. I am installing the oil catch can tonight so everything should be fine. Thanks for the help in getting to the root cause.

Jeff