How often are you allchanging your spark plugs??

most do it at the recommended 120k. are you burning much oil?

 

do you have any pics of old plugs? i can't imagine what else might be fowling them. even at 120k, many say they look almost new.

how many miles on the car?

are you using plugs from a dealer?

 

For our vehicles with Iridium plugs, it's every 10-years or 100,000 miles. Non-iridium are every 5-years, 50,000 miles. I, also, replace the PCV valve when I replace the plugs.

 

Whats a plug valve?

How were the plugs fouled was there oil on the tip or oil around the base? If oil on the tips the rings are shot.

Hope you used factory coil on plugs after markets are worthless. After markets are half the price of a factory cop for a reason.

 

The PCV valve routes air and fuel from the crankcase back through the intake manifold to the cylinders. It's actually prettty easy to check them...you just unscrew and then shake them...if you hear a sound like a ball bearing is hitting then it's working. If no sound or muffled or very hard to get the sound then it's clogged and need replacing.

 

Ok oil on porcelain is a leaky valve cover gasket
Very common in all 4 cylinder cars.

the fact that you see oil up that high on the plug means the gasket is shot. That high means the coil can get fouled too

happened to my g2 but caught it before it got bad.

to all lurkers before u take the plugs out remove the coil then take a picture of the spark plug well to see if you have oil in the well.

very common.

 

PCV valve relieves pressure from the engine crankcase which includes heated oil vapor and combustion byproducts. If you use crappy cheap oil or dealer oil change there will be significant oil vapor byproducts which tend to clog the throttle body becasue cheap oil breaks down with highly heated.

PCV valve feeds the throttle body via a small rubber hose. It is fed below the throttle butterfly. There is also a larger companion hose from the valve cover that also goes to the throttle body. It feeds above the butterfly.

Its important if you change the pcv valve that you also inspect the hose ends for cracking which i found on my car and also hose out the tube on the TB that the pcv valve hose feeds with cab cleaner as that TB hose connection tends to get clogged with gunk which you can see in my picture. This is not unique to a Prius all cars are like this with the gunk.

FYI: the hose that goes from the PCV valve to the TB is a special hose with a tight right angle. Its hard to substitute that hose given how crowded the pcv valve area is. A after market hose cannot make the turn with out kinking. I know I tried a few. That hose was $35 at the dealer and they stocked it so its a maintenance item also.
See my picture.

If your running DINO oil it will be very badly clogged negating the pcv effect.

Please see the pictures of my throttle body. See the 2 hose connections. See the smaller hose connection filled with gunk.

And as far as oil leaking past the valve cover gasket into the spark plug well I included a pic of that on my car also as that was just starting to leak oil into the well.

 

PCV valve likely and hopefully it wasn’t for too long.