Sticky intake manifold, dry and clean EGR, why?

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17,910
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Silicon Valley
95 Corolla 1.6L (4AFE engine) Previously I had a thread about a barely passing SMOG test due to high NOX and most suspect a stuck EGR. So I spend some effort taking out the EGR and its pipe (due to a stuck nut) together and found the inside to be very "free". There is a grey surface that I'm not sure if it is oxidation or just the material choice, but it wasn't wet or sticky. Parts cleaner seems to do nothing other than turn a bit brown/orange. However while look at everywhere for potential blockage, I notice that the intake manifold past the throttle butterfly is sticky. Should I go ahead and clean it with something? Will it help fuel economy?
 

JHZR2

Staff member
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46,293
Location
New Jersey
The edges of the TB butterfly and everything "inside" from there will have gunky black dirt in it because of blowby, PCV gasses, etc. That is normal. You can clean it where your eye can see, but Ive never seen it to make a big difference.
 
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36,528
Location
ME
^ +1 PCV gas is where your oil's from. If you ran a breather filter (don't), you wouldn't have an issue. When you park the car, the throttle is closed and there is then oily misty air inside the intake manifold that has no choice but to condense.
 
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