2014 model suddenly running rough

Well then maybe you should also mention that in order to do the job right, the head(s) need to be sent to a shop to check for warpage and to be milled if necessary.

 

Doesn't matter what you got, what matters is where you got them from.

 

The only way that matters is if they are not the genuine article.......and are counterfeit parts.
Maybe you should have explained that.

 

Regarding getting steam and water coming from the tailpipe... that is normal, the catalytic converter converts unburned hydrocarbons (fuel, etc) to water and CO2, among other things.

Posted via the PriusChat mobile app.

 

So does the engine, in much larger amounts.

 

Totally BAD information.
A little moisture when the engine is COLD is normal.
Any other time it is NOT normal.
The catalytic converter is NOT THERE to deal with "unburned hydrocarbons".

 

This Sam Spade 2 is quite the diplomat although it is hard to pick up on that in this thread. What happened to the original Sam Spade? Banned?

 

Anyone ever tell you it’s impolite to talk about present company in third person? Derisive comments especially?

 

Can be lots of different things that cause a misfire- ignition (plugs and coils), fuel (injectors, vacuum leaks), mechanical (compression), "misc" (EGR or coolant faults).

When does it misfire? All the time- only on cold start - at idle- under load?

Check the ignition system (again). Minimum - pull the coils and plugs for inspection and swap parts around to other cylinders. If the miss follows a part - that part is bad. If the miss stays- go fish.

Typical early indicator of a head gasket problem is a miss on cold start that clears up after a short time. The gasket seeps just a little after sitting and that small amount of coolant will foul the spark plug until it "dries off".

Testing involves pressuring the cooling system when warm. The next day, remove the plugs and inspect the cylinders for coolant with a videoscope.

EGR system is only operational under load when the engine is warmed up. A clog in part of the intake causes unequal EGR flow and misfire- but only under load and not cold. If the valve sticks open (which would cause unwanted EGR flow and rough running at idle) then it should set a "stuck EGR" code.

Posted via the PriusChat mobile app.

 

did you clean the those intake manifold ports?

 

What I said in this thread is absolutely TRUE.
No diplomacy needed.

And the original account was damaged in a system "crash" a few years back.

 

It never overheated.......that you KNOW about.
And sometimes they warp from "normal" operation over LONG miles or from improper initial installation.
A real mechanic would know that it needs to be checked.
While it is somewhat rare, they might find that the head is actually cracked.

 

Toyota offers a "gasket kit", with head gasket plus pretty much everything else pliable inside the engine, even valve stem seals. I think they actually offer two such kits, the second one a bit more extensive. You'd need to research the differences between the two. I think the one spec'd in the attachment is the less extensive kit, but I'm not sure.

I've heard here that the FelPro gasket is superior in some way, it's structure is a little more forgiving of slight warpage? I've no clue myself.

Just weighing everything, and considering that both 2nd and 4th gens have had very few head gasket failures reported here (I don't think there's a single confirmed 4th gen failure), if it was me I'd go for the Toyota kit. And new head bolts, just to eliminate that variable. The Repair Manual has specs for the head bolts, says you can check and reuse them if they're within those specs, but for a one-time DIY job, new bolts maybe helps you sleep more soundly.

Attached has part numbers for Toyota head bolts and the gasket kit:

 

Changing a head gasket on a Prius is not a good first time job. So I assume mechanic 101 instruction is not needed.

Yes the head should be professionally inspected, cleaned and rebuilt by a machine shop. Ideally it does not need milling as this has been known to cause problems in itself especially if excessive metal removal is required. Timing chain is critical and is often the cause of rework as are other gasket leaks. Head bolt torque issues can cause another head gasket fail. Intake should be replaced and egr cooler cleaned or replaced. Most startup issues are disconnected connectors.

Often a rebuilt engine is an easier and far better solution since it replaces the rings.

 

Attached will help, has procedures and specs.