2011 Prius sounds horrible after cleaning EGR cooler

If you didn't clean the ports on the intake manifold, you only did have the job.
Like replace 1/2 the engine oil.
Remove the intake manifold and clean it out. Clean the sensors with the proper cleaner.
Clean out the 4 holes for the egr gases with gunk and a .22 bore brush in a drill. It will only take a
few seconds for each hole. Clean the whole manifold and reinstall it.
This will probably take care of that miss fire. If not, switch the plug and coil with another cylinder.
If the miss fire follows, you know it's either the plug or coil. Switch the coil back to #4. Then you'll know if
it's the plug or coil.

 

The intake manifold carries EGR to each of the four ports through small passages. Carbon buildup only needs to be sufficient to mess with the flow through the small passages, and then you end up with some cylinders getting too much EGR and some getting too little.

 

It’s part of the EGR.

don’t disconnect throttle body coolant lines btw. They have sufficient slack.

 

Sounds like the original problem is still there and all the egr work was fruitless other than as general maintenance.

Given that the egr is closed at low loads and wide open throttle, it could be staying open, eg still "sticking" even though it has been replaced. It could be more open than commanded. Egr flow at low loads can foul plugs. Normally one would think wiring or control if the egr valve is new but new parts are sometimes faulty as well.

Or it could be the oil sloshing around in the intake manifold, routine on these engines. That oil is bound to get into the cylinders and cause plug fouling misfires. Which causes a loss of sync with the motor generators and resulting clutch damper slippage.

Given it goes away with the egr disconnected I would focus on the egr.

 

Did @GeekPriest ever disclose the miles on the odo?

 

Considering that the 'last mile' of the EGR system, the small passages in the intake, never got any attention, and that's the only part of the EGR system where a problem can escape detection by the MAP sensor, there's a step that's calling out to be taken.

I am not betting on the new valve somehow sticking open, because if it were, electrically disconnecting its motor would not close it, and yet the OP is seeing behavior change from electrically disconnecting it.

 

Great!

 

Recently I cleaned two egrs on two different cars.
You must to do cleaning for the inlet manifold. And pcv valve.
And to clean your throttle body.
It's easy for you. after the egr?!

 

Also occ can was installed on both cars.
It will eliminate oil burning by your.
engine. Good idea.

 

I don't think so. It'll help, but:

1. No OCC is 100% effective. It might waylay 50% of the airborne oil droplets in the PCV air? At most.

2. PCV systems pulling oil into the intake are only a small part of the oil consumption reasons. Other big factors are clogging pistons/rings, and failing valve stem seals.

 

Agree. Excessive oil burning generally means scored and uneven wear on the cylinders. Initial causes include oil rings clogged such that are not free to move. Made common by poor design in certain models including the 2010-mid 2014 Prius engines.

Other Toyota engines have low tension rings which were employed to improve mpg. Those engines can also develop excessive oil burning which is defined by Toyota as one quart every 600-1200 miles depending on the engine. It is easy to see that a 10,000 mile oil change interval could burn all the oil two or three times if not checked religiously. Even 5,000 miles could run your engine out of oil.

Concerning oil catch cans, the better versions have sintered bronze filters and larger capacity. Some later gen Toyoya engines have them built into the engine with a mechanism to automatically drain the oil back into the sump. If an aftermarket catch can is not monitored it could fill and build crankcase pressure, potentially causing leaks. Which is one reason Carb States like California don't allow them. If the average driver can not be relied on to check his oil, the aftermarket catch can has little hope of being monitored. Some require removal to empty making the absent minded problem more of an issue.

 

I am surprised that few if any Aftermarket Catch Cans have the self draining feature. Even a drain tube with a valve on the end, that is fed down next to the oil filter would make it easy to empty during each oil change.