The head on my 2010 is pretty cruddy, so the EGR Cooler/Pipe/IM cleaning will be well worth it. What also bugs me is the amount of crap around the valves and on top of the pistons (viewed via scope). Has anyone tried a top engine clean like we used to do on older engines, where you put a vacuum hose into a can of GM TEC, suck the can empty while trying to keep the motor running?
The trick I would try is Seafoam Spray. It has a 8-12 inch hose, along with a piece of molded plastic. You clamp the plastic with the hose on the throttle body using the clamp for the intake hose. Then an assistant keeps the car running (Power mode in Maintenance Mode) so you can maintain 2k RPM. It takes 7-10 minutes to empty the can. Take the car out in the middle of nowhere, as it gets very smoky.
None of the other 4 cars that I have used this method on have suffered any lasting ill effects. They do smell until you take them out the highway for a couple of miles though. LoL
I had a top engine clean done on my '08 and then the check engine light came on and the tech said the Catalytic converter is bad. Car was fine going in for oil change came out with needing converter replaced. I was angry and told them that they broke it doing the engine clean. So now I am stuck. Is there anything I can add to the fuel to clean the catalytic converter? I had someone tell me to put about 3 gallons of racing fuel in the gas tank and it will burn the crud away. I hesitate to do this without chatting it out with you all. BTW, my Prius has over 200K miles, runs great, gets 45mpg. I cannot afford to replace the converter, part alone was going to be $2200.
Cataclean claims it will clean your catalytic converter. Add two bottles to half a tank of fuel and go on a road trip with lots of high speed driving. Or the alternate method is add a gallon of acetone to a full tank and then do the road trip. Some people have better luck with cataclean than others, that is why I think two bottles works better. Cataclean - Fuel & Exhaust System Cleaner
I also had after doing the EGR system cleanse. It looked bad enough that I was afraid of knocking off a chunk and having it ricochet around the engine or get lodged in a valve. What cured it: a few bottles of Techron concentrate and time. After a couple of years I removed the intake manifold to clean it again and the head was void of carbon deposits with a light oil coat. Some of the fuel injected gets belched back into the intake manifold during the Atkinson cycle of the 2zr-fxe engine. It makes fuel system cleaner very effective against this sort of thing.
Unprofitable experiments are forgotten while profitable ones continue (see my sig) Ray, thanks for the Hybrid Automotive suggestion!