Still have P219A - Rough at Cruise Speeds - Cleaned IM Already

How did you pull the codes, or what device did you use?

Is that the only code?

How many miles on your Prius?

 

How was the pipe, how clogged?

I'd second the miles question, it's pretty much the yardstick for egr build-up.

 

Did you replace the intake manifold gasket? Sounds like bad A/F mixture

 

The cooler is what clogs. You only did part of the job.
The pipe can be clean, but if the cooler is clogged it won't matter. You were so close, why didn't you complete the job?
NOT MAD! Just wondering....

It would be like changing 3 of the 4 spark plugs that are all broken, the engine won't run correctly.

 

Cleaning the pipe is easy, and good to do first, because it gives an idea what the rest is gonna be like.

Cleaning the rest I would budget a weekend of down time, especially the first go 'round. The wipers, wiper motor, windshield cowl, all need to come off.

Coolant lines need to be disconnected. I found preemptively draining a couple of quarts of coolant into a clean container a good ploy, then the EGR system is completely above the coolant left in the system. Just pour it back into reservoir when everything's reassembled.

The EGR valve/cooler assembly doesn't surrender easy: there's about half a dozen connection points, the aforementioned pipe needs to come off, connection to the exhaust manifold (watch you don't drop the gasket at that connection).

There's one nut on a stud at the underside of the cooler that's nigh impossible to reach. It is possible, but there's so much in the way, it's blind. One consolation: the stud can be left on. If everything else is disconnected first, the nut removed from the underside stud, then the assembly can be lifted off. And consolation number two: leaving that nut off at reassembly, the whole thing is still very sold, makes it easier if you ever revisit.

There are other studs that do need removal, for those you need an E8 Torx socket. If you ever want to remove the studs on the intake manifold (throttle body hold-down) an E6 socket is needed.

Again, the removal and install can be done in 5~6 hours, but considering head scratching, screw ups, and protracted cleaning of the cooler/valve, budget a weekend.

 

I got to the "impossible" nut by using a short extension and a socket, slip it in from the side. Comes out nicely. Can't use a wrench (no torque possible with the little wiggle space)

 

Try some 100% gasoline without ethanol(E0). Sometimes that smooths out some roughness. Closest to Lima, Ohio is:
Casey's General Store
100 S Dixie Hwy, Cridersville, OH; 419-645-4455; ethanol-free CASEY'S 91(octane?)
Probably won't need 91 octane. Check pure-gas.org for stations with 87 octane E0 in the region.
Ohio has little 87 octane E0, however. Curtice has some 89 octane E0.

 

Do a leakdown test and report back with your findings.

Some of the non-atkinson cycle versions of the 1.8L had issues with the cylinder head. More info on this here:
Download Rate Exceeded

 

I can understand that.
But it's not near as hard as some people are making it. It's very easy to remove the wiper assembly. Only takes about 10 minutes?
Removing all the nuts and bolt was also easy. Just take your time. And depending on the tools you have it goes quickly.
A 1/4(snap-on) swivel helps for those hard to get at nuts, bolts, and studs. I have a 2010 and everything came right out.
This was a job I've never done, and by watching the videos, and making adjustments, I had everything apart, cleaned,
and back together in about 4 hours.
Just make sure you have all the gaskets! I had to wait a day for the intake manifold gasket. I didn't think I needed it,
but the original one was squished and it would have leaked.
Draining some of the coolant would help, but I only lost about a cup of coolant so it's wasn't that big of a deal.
At least the only thing you need to clean is the cooler!

 

I only had time to skim, but I'd take another look at the MAFS first, just because it's so easy to rule out....then the EGR cooler...

 

Garage is NICE! Sounds like some a sensor is bad. Not sure what the Prius uses, but Mercades had a cold start/enrichment valve that acted the same way when it was bad. It always thought the engine was cold even when it was hot. The Temp sensor could be bad also. Or as ETC said, the MAFS could be bad. All things to check before you get somewhere warm to do the cooler.