VR v6 all 6 spark plugs carboned

Might be a faulty O2 sensor. I had a brand new one that was faulty from factory.

 

I think you hit them with a map torch and test the resistance with different heats applied.

 

While they still shouldn't foul up too noticeably, short tests while the car is cold aren't a real good indicator as the ECU will be dumping more fuel than usual into the engine to get it to temp. You really need to look at them after a drive where the car has been at operating temp for (IDK) like 10 or 15 minutes at a minimum maybe.

Does it run right now? The missing is likely to have caused them to foul up if it's injecting fuel and not combusting, then it intermittently combusts when there's heaps of fuel in the chamber which means the mix is rich fouling the plugs. What's the part number on the spark plugs?

 

A lot of the time it's a bit of viscous a cycle. The plugs foul for some reason (leaky injector, combustion issues, misfire), then in turn the fouing makes the initial problem worse via more misfire or whatever.

In response to your initial post, valley typically gaskets won't do this, usually they just leak oil into the coolant when they go. Are all the plugs fouled or just one side? VN-VR all use bank injection so if the plugs are all fouled on one side it's kind of telling. Other places I'd start looking are around injectors and the fuel pressure regulator, possibly the map sensor, also busted coolant temp sensor is one that would cause a lot of issues like this..

 

Given it's all 6 plugs, super unlikely to be injectors themselves. Trace the wiring loom for them back and see if they're frayed anywhere though. MAP is usually just a total replacement, you can't really clean them like you can with a MAF (MAP isn't a really common failure though, just something to be aware of).

Have you pulled any codes from the car?

 

With oil on the thread...If it's leaking from the rocker cover, you can generally see a line of oil, running from the base of the rocker cover to the spark plug hole....If you can't see this line, the issue is internal....worn valve stem seals (which is generally the issue) or worn piston rings...

 

Sometimes the guides wear, which doesn't help either. Some cars don't always have valve stem seals if the guides are still nice and tight. I rebuilt an old 75 engine years ago and it never had seals. The guides were pretty fucked though and it burnt oil even after rings and a hone. But I didn't want to spend money on a Repco change over head, so slapped it back on.

Glazed bores will cause oil burn as well.

 

Eco is pretty similar in a lot of ways to the Buick. It will have guides. The valves wouldn't stay in place otherwise. I'm pretty sure you can change the valve stem seals without removing the heads. You might be able to check the guides at the same time, but it's heads off to replace them.

 

Internals are reasonably similar. They improved some aspects of the V6 when they went to the Eco.

 

I have an idea that the Buick heads will actually bolt on to an Eco but that would be as far as you would get.