Moderator: volvite
As I said, I replaced the PCV valve and none of the hoses seem collapsed. There are three ports going into the air duct - one of them is allowing oil into the air duct, and it's dripping into the air mass sensor and onto the air filter. Which of the three ports (the two you can see in the pic https://i.ebayimg.com/images/g/DhkAAOSw ... s-l400.jpg and one more very small one that seems to go to a vacuum switch of some sort) could oil be coming from?VStar650CL wrote: ↑Tue Dec 14, 2021 3:34 pmMost likely a bad PCV Valve, could also be a collapsed hose in the PCV system or a clogged air gallery inside one of the valve covers. It's probably causing your poor performance as well.
Thanks! Great! I'll give that a try. I sort of rely on folks' knowledge like this - that "the oil only can go through the PCV system." I replaced the PCV valve which is unique from any I'd ever seen before. it has a pipe fitting on one end that screws into the intake manifold near between two injectors, I think. I'm not sure where the other end goes - I guess to the crankcase somewhere? PCV valves are usually press-fit into the top of a valve cover, right? That's why this seemed so odd.VStar650CL wrote: ↑Tue Dec 14, 2021 8:52 pmSee if you can blow through the PCV passages from the valve covers into the crankcase. You may have a clogged cover. Oil really doesn't have any route to reach the MAF except via the PCV system, so either your problem is there or something very unusual is pressurizing your crankcase.
Oh, wait - the PCV valve screwed into the intake manifold near the injectorsVStar650CL wrote: ↑Tue Dec 14, 2021 8:52 pmSee if you can blow through the PCV passages from the valve covers into the crankcase. You may have a clogged cover. Oil really doesn't have any route to reach the MAF except via the PCV system, so either your problem is there or something very unusual is pressurizing your crankcase.
Yah, the VG engines weren't the easiest to work on, they were all PITA's in one way or another. Here's a diagram of the PCV system from the '93 SM, but I'm pretty sure it's the same back to '89. There should be a crossover tube from the other rocker cover as shown in red. Those tubes, the valve, the breather box, and the baffles in the rocker covers all need to be clear, anything plugged in any part of the system will cause oil to regurgitate in one or more places.PattiM wrote: ↑Mon Dec 20, 2021 9:17 amIt looks like the PCV valve tube crosses under the intake manifold to the top of the passenger-side rocker cover near the back of the engine. One of those two 1/2-inch tubes coming from the air duct/boot thing goes straight to the front of the same rocker cover - so I guess that's an air *inlet* for that rocker cover? It seems like that would be the most likely place for oil to get to the MAF - it comes into the air system only a few inches from the MAF.
EDIT-2: OK, the other tube goes to something called an "Air regulator" on the side of the engine.
Maybe I should try "blowing out" the PCV tube?
Could you look in your manual for the two 1/2 inch diameter inlets on the air duck and see what they're connected-to? I found that the one closest to the air filter housing connects to the front of the passenger-side rocker arm cover, but I can't figure out where the other one goes (the one closer to the intake manifold).VStar650CL wrote: ↑Tue Dec 21, 2021 9:23 amYep. I couldn't find that section here in Nico, but it's in the EC section of the FSM.
Thank You! I'd really appreciate that. I'm hoping that whatever is putting oil into the MAF sensor is what is causing this engine to run rough. It used to run rough only occasionally (once every couple of months for a few minutes). Now it's constantly running rough. Plugs and compression are OK - so it's some feedback in the engine control system...VStar650CL wrote: ↑Sun Dec 26, 2021 8:30 amI'll have to look on Tuesday, I'm not at the shop and don't have access to ASIST. If I haven't posted anything by around noon Tues, freshen-up this thread to remind me.