What is this oil in the hose back of plenum

[darmie]

2006 mazda b3000 3.0. Today I planed to replace an injector but I was not able to remove the fuel rail. I was having a cyl 5 misfire and found that this plug was wet, so, I was thinking that the injector leaked down. When I pulled the hose off the back of the plenum that goes down to the valve cover, it was dripping a good amount of oil out of there. What is this all about and how do I fix it. I wasn't able to remove it completly for there was some type of insert inside of the hose going to the plenum. I also wonder why is there a 2 wire harness going to a plug on the other end of this hose going into the valve cover.

So, now with a bit of wet oil on the intake side of the plenum, I'm wondering if this is the reason for my hard starts and not a leakdown of an injector. Morning starts are find, starts in a few minutes of turning off the engine is fine, but when it sits for a while, it's hard to get started, have to turn the motor over several times before it starts and this sometimes followed by the engine running rough for 5 to 10 seconds.

 

[Rearanger]

When I pulled the hose off the back of the plenum that goes down to the valve cover, it was dripping a good amount of oil out of there. What is this all about and how do I fix it.

More than likely this your PCV connection. Oil misting is sucked into the hose and intake from the valve cover. Unless you're getting excessive blow-by there's little you can do as I think this is a weakness in design by Ford. On my truck I installed an oil catch can so that oil would collect there and not make it's way to the intake. I doubt this is your source for the misfire and rough idle.

I also wonder why is there a 2 wire harness going to a plug on the other end of this hose going into the valve cover.

It may be a PCV sensor that will tell you if the PCV is not operating properly.

Your problem could be injector leakage. You can send the injectors out to be flow tested, repaired and cleaned for about $15 per injector which includes a before and after report. There are a number of companies advertising on the internet for this service.

 

[srteach]

Before you tear into it too far, test the fuel pressure at the schrader valve on the fuel rail. Test it before first start, while running, and after a short off time. See if the pressures are the same. If they are, the problem is not fuel leak down or an injector. If they are not the same, you need to find where the pressure leak is, and it may not be injectors.
Turn the key switch to run, but don't start it, several times to see how far the fuel pressure rises. If it comes to the high pressure with the first key turn, the pump is not likely to be weak or a problem.
Once you get the fuel system to full pressure, watch to see how fast it falls (if it does). Fast pressure fall may be the check valve in fuel system, slow may be an injector.

BTW, the fuel pressure should be in excess of 34psi (36+ is better).