Head gasket troubles, seeking advice

The coolant that is getting into your combustion chamber is just a vapor initially and then when you shut your car down the cap that's on the digest bottle allows X amount of pressure to stay in the system that pressure staying in the system is pushing coolant out of the leaking head gasket in the number one cylinder bore. If you were to take that Degas bottle cap loose hear the whoosh leave it sitting loose when you come back out to the car I bet it doesn't rattle on startup because not enough water is getting pushed through the head gasket when there's no PSI behind it at least that's what goes on in the early part of the head gasket failure so right now if you were to suck the bottle down to about halfway and leave the cap loose and drive the car you'll almost have no stutter at all when the head gasket gets worse then it will stutter no matter where the cap is at that point you need to start thinking about doing something then Right now you may be able to drive another two or three weeks depends on how much highway and mix3d use and all that

 

This is pretty much normal for the 2ZZ Atkinson cycle engine so you're going to have real trouble sorting this out it'll just well maybe happen again apparently the generation 4 did some stopgap measures that may or may not have shored up the problem. But I'm kind of doubting it so be interesting to see how this goes I have other half that does the same kind of work and she put 396 on hers but it stayed in the wind and was never out of service I believe that's the only reason it made it to that mileage.

 

Leave the codes be, swap coils, say cylinder one and four, and see if the code changes.

Intake manifold too?

 

Very possible in early stages of hg leaks. Coolant loss is not obvious.

This behavior is late stage hg leaking. You will see coolant loss very soon.

Bad plugs or coils usually stay bad and don’t clear up. Plus the plugs can make 200k miles and the coils are usually lifetime.

 

Early HG issues give a misfire on cold start, but once the engine starts and warms up, the HG compresses and seals the leak. I don't think you have a HG problem since it's not misfiring after the engine is warm?

 

Or the overnight sit allows a slow coolant leak to go on long enough, for sufficient coolant to accumulate in the cylinder, hamper the piston as it tries to compress the uncompressible. Once that disipates, you're ok, till the next overnight sit.

 

A leaky egr valve can cause a misfire. Vacuum leak. Clogged injector. A number of things can cause a misfire. You should positively confirm it's the head gasket before going down that road.

 

As I had the same problem at almost the same mileage, firmly it's your head gasket, and the main issue came from an unfunctional water pump; replacing the head gasket and water pump is the best advice.
Mostly, on most of gen 3, you find the leakage on 2 or 1. After a while you will hear some bubble noise from heater.
For the love of God never use any sealing solutions.

 

Just for now, whenever shutting off the car, once open the reservoir cap to let the CO2 go off and then tighten it. It prevents the leak of the coolant into the chamber overnight.

 

Good suggestion leave the hood up and leave the reservoir cap untwisted overnight You can leave it sitting on top of the jug if you're afraid something's going to fall in it but just leave it off because pressure can come back after you close the jug right after you let the pressure out because the engine is not fully cool that takes time pressure will build back up in the seepage wheel or can continue so just leave the cap loose the hood up and maybe with the hood up you'll remember the cap is loose you walk out in the morning tighten the cap drop the hood ready the car and go You can also drive the car in most all weather but extreme heat conditions with the cap loose on the jug I did this for a long time in a generation 3 drove the car till it blew up actually We weren't waiting to fix it It had many other problems that weren't worth our trouble.