So I got the Haynes book (somewhat useful, but missing lots of info), and took the IM off myself. Good news is I got it off, cleaned the suspect orifice in the service bulletin, got it all back together, and it runs fine with no check engine lights. Also good, my expense was just some Gumout and a new throttle body gasket, not the $630 the dealer quoted.
The bad news: The orifice wasn't clogged after all
. I ran a drill bit into the hole like the service bulletin says, but didn't find anything in it. I stuck the little tube from the Gumout can into it, and spray started coming out of holes near the intake ports, so it doesn't seem to be clogged after all. Wasn't such a bad exercise anyway though, the intake manifold had some oil pooled in the bottom, and it was grimy inside. The throttle body also needed cleaning. Also glad I didn't pay the $630 to have the dealer find out it didn't fix it. I tried blowing a shot of Gumout into the port in the cylinder head that feeds the little orifice, put the nipple from the blow gun on my air compressor into it, and I could feel air coming through the filler cap. I don't think that port is clogged either. The breather tube that goes from the air box to the valve cover is also clear.
Now it's running the same, and I can still feel puffs coming from the oil filler and breather. The receipt from the dealer who diagnosed that the PCV system was clogged says there was no change in fuel trim when disconnecting the breather line, which points toward a clogged PCV instead of bad rings. Does that sound right?
Any ideas? Here's the recap:
-2013 Chevrolet Equinox Ecotec 2.4 burns about 1 quart/1000 miles.
-Service bulletin mentions clogged PCV orifice in the intake manifold as the usual suspect. There is no PCV valve to replace.
-Dealer confirmed positive crankcase pressure, diagnosed it as clogged PCV system. Dealer says service bulletin does not apply to our VIN.
-Intake manifold orifice was not clogged. Cylinder head port to the valve cover does not appear to be clogged. Breather tube from valve cover to air box is not clogged.
-Engine runs fine, but there is still positive pressure coming from oil filler cap if removed, or from breather tube port if it is unhooked with the filler cap on.
Any ideas? Is it starting to sound like maybe it really does have bad rings and maybe what I'm seeing is just lots of blowby?