got a 93 s10 blazer 4x4 with the 4.3 vortec vin w. im in the process of changing out the intake manifold gaskets and when i pulled the top intake plenum off it looked real dirty on the right side and just dirty on the left. but anyway i found little puddles of oil in the low spots and lots of carbon build up in the intake ports. Why is the oil there? and should i be worried about the massive amounts of carbon build up?

 

A dirty plenum is a good thing. If it was really clean and golden looking then you would have signs of a fuel leak. Is there alot of Oil puddled in the plenum? Remember your PCV valves goes into your plenum so you will get some oil and it will build up after a period of time. Best thing to do is get some rags and wipe up as much as you can and spray the plenum down with some carb cleaner to clean out the intake runners.

 

No there is not that much oil in there. maby enough to fill a teaspoon up or so. Like you said it probaly came up through the pcv valve. forgot about that. but i got the top plenum somewhat clean with a can of carb cleaner and some air intake cleaner i had laying around. took some shop paper towels to wipe it down with. pulled chunks of carbon out of the egr valve hole. about as big as you pinky finger. im gonna get 4 cans of carb cleaner tomorrow and wash it real good. what should i do about the bottom where injectors are? should i just shoot it with carb cleaner and just let it run down and not wipe it cause i dont want to really disturb the injection system cause its like 280 bucks to replace. and the left side looking at the front of the engine is a little lighter than the right. but isnt really clean at all.

 

you can take some shop rags or towels and mop up the oil and use the carb cleaner and wipe it down, just be slow and around the injectors. good thing for cleaning out the EGR, probably be best to remove it and clean out any carbon build up around there. you can get a EGR gasket with a screen in it to help prevent some of that carbon from getting into the EGR valve.

that lightness could have been an old fuel leak from the FPR(fuel pressure regulator) the round cylinder looking thing coming off the Spyder or a new slowly growing leak. usually the FPR is the bad piece of the Spyder, not the entire Spyder like some people think. Thats how some garages rip people off, saying its the spyder which like you said costs $280 dollars. when its only the FPR which only costs $50.00.