Professional EGR Cleaning Resources

I BIG thanks to ya! Will do!

 

Thanks to you all. I will schedule the borescope test tomorrow and go from there. -- But could coolant still be getting in there, even if I never have to add coolant? LIke I haven't had to add any in a couple of years now at least. But it sure sounds like what's happening because it runs good the rest of the day. -- Oh well, I will let you all know what I find out. Thx again for all the support!

 

Make sure the coolant system is pressurized and the mechanic knows gen3 Prius issues. It just takes drops of coolant seeping in overnight.

This is how to do it

 

I am afraid it is head gasket @Scottyboy24
Classic random misfire in a cold Start. EGR clogging effects the drive in mid throttle after the engine is warm

Check the coolant level, and start shopping around for a used 2015 engine. That's the most cost effective way unless you can find someone replace headgasket for less than 1000$.
How much the oil consumption? if it is less than 1q per 5k miles, then it is worth to fix it. Otherwise, time to move on
The head gasket at around 150-250k miles is very common on 2010-2012 Prius. The 2013 model has less issues but not immune. The p0300 random misfire, p0301=cylinder 1 misfire, etc. Bring it to mechanics to do a pressure test, otherwise the coolant level already gives a clue. The coolant level should stay the same over 5y in most Prius.

I am very sorry, but we should plan cleverly. How much is the car worth, and the rest of the car condition. Head gasket in Prius pre 2015 is known problem and we must be wise what to do next. Check oil consumption, and prepare for catalytic converter too if it excessively burns oil 1Q/1000 miles.

 

The P0300 is the ECU knowing there's a misfire, but can't nail it down to a particular cylinder because the engine is rattling so much. @johnHRP does a good job explaining this and the main misfire is in #2.
I would call local parts stores to borrow a bore scope. Remove the spark plugs and inspect the top of the piston heads. One or two of them will be different from the rest, that's the one getting steam cleaned by your coolant leak, if it's a head gasket problem. If that isn't the issue, move spark plug #2 to #1 and #2 ignition coil to #3 to see if your problem moves. If the problem moves, that's the intermittent part that needs replacing. At that kind of mileage, If it is a failed plug or ignition coil; I'd replace the set - but don't shot-gun it if it's a head gasket. You'll need to determine if it's worth fixing.
BTW: the electric coolant pump tends to get intermittent, lazy, and/or die at that mileage also. You need to monitor the ECT to make sure the engine isn't running hot, might be another reason the head gasket blew. The ECT icon doesn't trip till +240F, normal operating temperature is around 190F. Some people claim that they don't have a problem because it only flashes on and off a few times. Your engine is running too hot. Start saving up for a major repair....

Hope this helps....

 

Throw parts at it without leak down test first with those codes?