Severe Engine Misfire

The truck is a 2013 CM 4x4 Tundra with 200k miles.
This morning on my way to work, I was driving about 70 mph on the freeway when I began to feel a sudden misfire. After about another minute or so, it started to misfire in additional cylinders. I limped the truck to work where I parked it. Previously the truck ran great. The codes are attached. I tried cleaning the MAFS, checking for any leaks using a smoke machine, and doing the usual ignition coil/spark plugs check (iridium plugs also changed roughly 35k miles ago). No obvious hoses disconnected and no cracks or breaks from the naked eye, but also I am new to diying my cars. Any idea of what this could be and any suggestions on what to check/do before I pull the intake manifold off to check the gasket? It sounds something is puffing from what seems to be the manifold. The engine is also bogging down at idle, and seems to nearly stall. Increasing rpms helps it slightly, but it still misfires.

https://youtu.be/OgVA7dtxtSY?si=dD8yfnLE-ivdS2aZ

 

Why dont you list out the codes - I do not like having to download a file just to read soneone elses codes - could be malware there.

 

I would look at the battery and the connections first and then change the fuel filter. Just my guess as a starting point. The messages about the various systems looks like it might be battery related.

 

Sounds like a massive intake vacuum leak

 

My mistake. Codes are P0301, P0300, P0303, P1605, C1201. I also had multiple misfires in cylinders 4, 5, and 8.

 

I checked the battery terminals and even disconnected the negative terminal for an hour to see if it would reset (didn't expect much), and I saw nothing loose or of concern. As for fuel filter, I believe it is integrated into the fuel pump assembly, so not as easily replaced. I believe the trac control code is due to the limp mode? I'm not 100% sure, but appeared the moment the misfires started.

 

Yeah, that is what I am thinking too. Would that be something that happens all of the sudden, or is it something that would progressively worsen? My issue appeared with no warning signs. I was initially guessing intake manifold gasket, but I am wanting to verify that it makes sense prior to pulling off the manifold.

 

Vacuum leaks in the manifold this bad don’t just show up like that. My guess is a failing fuel pump or fp module. Start your troubleshooting by observing afr’s and fuel pressure.

 

Vacuum leaks can show up suddenly, when a vacuum hose fails. I’ve never heard a failing fuel pump make that awful pump sucking noise.

 

Agree with that but op said he checked them all for leaks. Didn’t equate “puffing sounds” with a leak. Op, pretty easy to check for leaks. Run a idle and spray carb cleaner around ANY area that could be a vacuum leak. If idle rises, the area you were spraying has a vacuum leak.

 

Finally got some time at work to further diagnose. By accident I found that the intake manifold was about 180°f near cylinder 1's intake port. The rest were about 90-100 °f. This lead me to think it was something related to that specific cylinder which made sense since the loud exhausting sound was coming from the front of the intake manifold. I then performed a compression test on all cylinders, 0psi on cylinder 1 the rest were about 180 psi +-5. Checked it wet, no change. I used a boroscope through the spark plug hole and it appears the valve hasn't dropped and the head has no damage or debris. So, next on my list is to pull the valve cover and assess the damage. I have seen quite a few threads of valve springs breaking, so that's my first assumption. Called toyota and they quoted me $10k for valve job, tried calling a few local shops and they said it wasn't worth their time. So, I think I am going to tackle it myself. Thankfully I work in aerospace and many engineers at my work have years of experience with automotive engines so I have help. But one question, does anyone know if you can remove the valve spring without needing to remove the timing chain and cam? I've seen people say both.

 

Should really do a leak down test before to see where the problem is. Especially if there is no obvious valve problems

 

Finally got time to dive further into my truck. Did a leak down test and found the air venting directly into the intake manifold and out the throttle body. Decided to take the valve cover off and found 1 broken intake valve spring on cylinder 1. Ordered springs, gaskets, timing chain tensioner, plugs, the whole 9-yards and I am going to try and tackle it this weekend.

 

Never done this on a Toyota, but worth researching to see if there is a trick to get the rocker/follower out without removing the cam tower. Would save ALOT of work. I have done this on other vehicles. Never investigated whether there is enough room to get a compressor on there with the cam in place.

 

Thanks for the suggestion. That's what I did. After looking into it, it is possible. And that's what I did today. I started by using a flathead screwdriver and popping the rocker off the hydraulic lash adjuster, then I slid the rocker out. Then, using a leak down test kit, I pressurized the cylinder at TDC, and closed the valve. Then, with a combo wrench, I used closed end of the wrench and the camshaft to press down on the spring. Since the spring was broken, it didn't require much force for the keepers to pop out. Then, I removed the spring. For installation, this was the tricky part. First, using a vice, I compressed the spring and used 100lb zipties to hold it. Then carefully, installed the spring. After getting it positioned in a way that I could cut the zipties, I installed the top hat (idk the formal name), and the keepers. This was the tricky part. A tip, use a flathead and gently push down on the keepers until they pop in place. Make sure you stuff a bunch of rags so the keepers don't fill into your head. After you get the spring installed, reinstalling the rocker isn't too bad. Rotate the engine so that the cam lob is pointed vertical. This gives you enough space to gently pry the rocker over the hydraulic lash adjuster.

I ended up doing just cylinder 1 springs. All in all, it took me 9 hours. Including removal of valve cover, installing 4 springs, installing new valve cover gaskets, and replacing all 8 spark plugs. I have no experience working on valves, but with enough attention to detail, it isn't too bad. I would recommend taking lots of photos, and triple checking all screws and connectors. Ran the truck until it warmed up and everything sounds perfect. All codes are gone, and she idles like a dream.

 

Great write up.