P0300 0301 0303 misfire and engine knock problem

Definitely clean the egr circuit stem to stern.

Use a pressure washer to clean the egr cooler as it makes the cleaning process very easy.

Add an oil catch can and you'll be good to go.

 

Replace spark plugs?

moto g(7) power ?

 

Good (actually vital) preventative measures noted above. Still, where you're at, the head gasket might already be failing. The codes you've got often lead to that. You could try swapping coils (label them first), see if the codes follow. I think best bet for checking the head gasket would be leak-down test.

 

That's a good point. If one can clean the EGR system DIY, without much $ cost, cleaning and hoping for the best is an approach. But, if one will be paying for cleaning the EGR system, most likely a costly endeavor, checking the integrity of the head gasket first, by leak-down or scoping, makes sense.

How well do misfire codes correlate to head gasket failure? It seems that recent history in PriusChat points to the head gasket being a common cause of misfire.

 

Yeah moving the coils around is a free (DIY assumed) move to see what happens.

 

Yes.

Then the oil catch can is separate .

But another good measure.

 

It's the usual dilemma: we would all learn the most if those things were done separately; if they're all done together and the problem goes away, no one will ever know what it was or which intervention solved it.

But then nobody wants to spend too much time diagnosing an ailing engine. (Just like asking someone with a scary illness to participate in a blinded trial, though it's the only way we can learn what works.)

Just have to wish you the best of luck with whatever way you're comfortable approaching it.

On the effectiveness of in-tank injector cleaner versus other injector interventions, we have some data here.

I wouldn't lose too much sleep over the gasket unless you acquire other evidence that suggests it. There's a folk belief here on PriusChat linking the EGR and gasket failures, very strongly held by those who hold it, but the explanations on offer never seem to get beyond 'truthiness', like,

• "Well, the EGR goes through a cooler, so if it's clogged, duh, combustion is hotter and there goes your gasket!"
• "Ok, truthy, but combustion goes from ?°C to ?°C and the gasket material limit is ?°C ?"
• crickets

It kind of stays forever in that perpetual limbo, while the unconvinced are sort of waiting to see better support and the convinced don't think any is needed.

 

Kudos to you for getting all of this done yourself. Hopefully cleaning all of this up, and maintenance gets you back on the road, running smooth as silk.

 

Did you get the small diameter EGR ports in the intake manifold? Sounds like you did, just wondering. Brushes designed for cleaning stainless steel drinking straws are good for that, with a little brake cleaner.

 

Brake cleaner is ok.

 

I had this same issue on my 2013 toyota prius 2 at around 180k miles. It started as rough starts then the check eng light came on with the #1 cylinder misfire code. I changed the coil pack and all spark plugs they were do for replacement anyways. Check eng light went away and things seemed fine for a day. Rough start came back so I did what you have done. I cleaned the EGR and intake Systems, replaced all those seals and the PCV valve. Things were good for a few days and then it came back. Looked in my intake and there was a small puddle of oil. Was thinking of getting an oil catch can but I didn't yet. I decided to borrow a borescope and check out the cylinders and pistons through the spsrk plug holes. I did this when the eng was cold and just seen gunk and put it back together. I decided to look at it again the next day but this time I ran the car before I pulled the plugs. When I scoped it this time I seen what looked like water drops down the #2 cylinder. At first I thought maybe fuel injector was leaking into intake but then I realized it was on the back wall near the exhaust valves. I watched as the drip would form and then run down the cylinder. It took about a minute for the drip to form. Then I knew I needed to atleast replace the Head gasket. I read on another thread that someone had the same leak in cylinder #2 . I never notice any oil or coolant loss between oil changes so it must have just started leaking. I have now completely torn apart the engine. I have decided to change the pistons and rings IAW the TB for excesssive oil consumption hoping that fixes the oil getting into my intake through the PCV valve. Good luck with your issues and I hope your ls is fixed. If it comes back try scoping the engine after it's been running. You might have to turn the engine over to change positions of the pistons to see better in each cylinder.

 

When you do the job next time, you'll be better prepared for it.

Cause there will be a next time.

Good luck and keep us posted.