Help diagnose a constant cylinder 2 misfire?

This is normal for this engine and this model Don't get too hung up on it because you can have a lot of money in it no matter who's doing the work Is the car in that nice of a shape to warrant winding up spending 3 to 5K If your time is free well so be it most people's time is not free they have places to be work to do etc so there's always that You're working on something that is pretty much planned obsolescence and executed very well by the likes of a company called Toyota and if you don't think they know how to enact plan obsolescence well you have another thing coming you're sitting in it Go back one year to a 2009 Prius and notice the huge difference in reliability and all of that Just one year it is amazing but a that's where we are anything you can do inexpensively I doubt it You see all the shops popping up around the country just to deal with this issue between 3:00 and 8K is generally what you're looking at Good luck the whole car isn't worth that at least not to me I have two sitting here please come get them

 

At 182k miles, with EGR semi-cleaned at 140k miles, and cylinder 2 misfire? Head gasket.

how’s the oil consumption?

 

You could score the Toyota gasket kit (includes head hasket), new head bolts, a tube of Permatex Ultra-Black and a 10 mm double-hex bit and have at it.

Do a thorough EGR clean while you’re at it, and consider an oil catch can.

full disclosure: never done anything like this personally.

 

Knowing the symptoms can be useful. Has it shaked and rattled on engine starts only to clear up as it warms up? If so how long ago did this start and how often does it happen now?

None of that is conclusive on early gen3 head gasket leaks. So much so I would not waste my time on a compression or leak down test.

A quality dual view borescope is a decent hg verification tool.

Early leaks are very small and depend on coolant pressure seeping into a cylinder as the engine cools. On a cold start, the plug may be fouled or may not.

When it’s an advanced hg fail it may shake and rattle after warmup and be noticeable with the coolant gas test. At that point coolant reservoir drops can be observed. Even later white smoke may be observed in the back as the engine is rev’ed. At that point the odds are good a hg alone won’t fix it long term.


Shudder video
“Hey Walt… they want to wait and see if it gets worse…”

Car Care Nut HG Borescope at 7:40

 

If this indeed is a constant cylinder 2 misfire as the thread title says, then the explanation probably isn't the "your head gasket leaked some coolant in while the car was off and you got misfires for a short time on startup" that usually leads people onto the head gasket story.

Misfires, as always, are a fuel-supply problem, an ignition problem, or a compression problem.

The famous brief shakes at startup head gasket issue is a failure of ignition; the cylinder charge with some coolant in it doesn't ignite. (If the leaked coolant is enough to cause hydrolock, then worse things happen.) That's the problem that reportedly is hard to see on compression or leakdown tests, because all that's happening is a small amount of coolant oozing through.

On the other hand, if that's not the story here, then the only other way this could be a head gasket issue would be if the gasket is leaky enough to cause misfiring by bad compression. And that should not be hard to see on a compression or leakdown test.

Or if it's not head gasket, it's back to the other causes of misfires. Other compression issues (burned valve, say), or ignition or fuel.

You've tried swapping spark plugs and coils. Have you tried swapping fuel injectors?

Is the misfiring really constant, or is there more of it at mid engine loads (not idle, not all out)? Although you did clean your manifold 42k miles ago, have you had it off since just to check the small passages?

 

I would certainly swap plugs, coils and injectors around to see if the misfires move. A borescope inspection would be my first test after the plugs are removed, assuming they look good.

The troublesome detail is the misfire already moved from 302 to 304. And there is some history of startup shakes that cleared. I have seen advanced hg cases where it misfires a lot but those were usually accompanied with white exhaust vapor someone behind observes as the engine is rev’d up. The vaporized coolant is not obvious from the drivers seat. The engine still runs and the misfires are not constant unless a plug has seriously gummed up and remains fouled, which happens. In these cases coolant level will drop if driven for any period.