jaredb03

I was taking off my intake manifold to clean it out because my car is running a little rough and has misfired some(no codes though). When i got in there i noticed that one of the intake holes?(not sure the term for them) looked clean and the the other 5 looked dirty. Didn't know what to make of it and was wondering if someone could give me some insight on why or what caused the 5 to get dirty but not one of them? Also how should i go about cleaning them? Ra

gs and carb cleaner i assume and is it safe to spray down into them? Thanks in advance

thisaznboi88

iTrader: (7)

blame the ERG valve

to clean it get a rag and soak it in brake cleaner or take off the lower runner, or get a set of port and polish runners

jaredb03

So its not uncommon to have 5 of them dirty with one clean? I didn't know if that meant something was wrong or not? Also the smaller hole to the right is pretty caked with soot any suggestions on cleaning that?

truonghthe

you clean it and after 10k miles or so it will looks like that again. Engine oil mist blowing from valve cover through intake throttle body and into the manifold. I would blame the EGR valve for rough idle.

Vlad_Type_S

iTrader: (3)

EGR and crappy PCV system. I replaced my PCV valve and run an oil with a VERY low NOACK value (6%, Redline 5W-30). Still, it's totally scummy. I think the only solution is to block the EGR and run an oil separator on the PCV system.

As far as cleaning goes, you might notice the intake manifold is kind of a shell. I would strongly advise against using brake cleaner here since there's a good chance it'll damage the rubber seal in between. (It's fine to use on the runners though, as long as they're off the car.)

I'm going to clean my intake manifold with really strong soap. Dish soap is good here as it won't damage rubber, just make sure it's the scent-free most basic one you can get so that it doesn't leave any crud behind.

Also, go ahead and clean the EGR passages as well, that might have been the cause of your misfire: some carbon got dislodged and went into the cylinder.