Persistent misfire in cylinder 4 of the 5vz-fe

Just curious if anyone else has run into a persistent misfire in cylinder 4 of the 5vz-fe, in the ignition system to be specific.
I had a slight misfire in cylinder 4 when I got the truck in the spring and it gradually got to CEL bad. Narrowed it down to ignition in another post so I swapped all the coil boots, plug wires, and spark plugs; it vanished, and the ocean was finally calm for maybe 2 hours of drive time. Then the idle shudder slowly came back but the loss of power this time is much more gradual. I should also note that plug for cylinder 4 was carbon tracking across the ceramic pretty heavily when I initially changed the plugs. I'll bring it to my buddy's shop and suck up the diagnostic fee in September, but until then, any direction would be appreciated.

 

Compression and leak down test

 

I did one as one of my earlier steps and everything turned out great

 

How about getting a spark plug tester (the little ones with a light that connect in line) and testing cylinder 4, vs cylinders 2 & 6? Might point to an electrical issue upstream causing intermittent spark issues. If you do this I'd pull the EFI fuse first and then it wont fire when cranking.

Did you use OEM plug wires and coil packs, along with Denso dual electrode plugs?

 

You said you did the coil boots, but no coils?

Maybe it has a bad coil. Move it to a different cylinder and see if the code follows

 

+1 on this!

 

X2

 

my bad I said that wrong I got the three new coils as well, the denso ones to be exact like these:
https://a.co/d/ceonb77

 

Smart! I’ll have to check this and come back and let y’all know, I used all denso products for the coils, wires, and plugs

 

How many miles? The injectors start to go around 200k. Almost always the misfire issue...

 

237116, I had thought of doing the injectors back in April but was told not to since I had found carbon tracking on the ceramic of cylinder 4’s plug.

 

I would do the injectors at that mileage anyway. Have seen enough of them cause a misfire in person, and on here, that it wouldn't be a bad investment. If you have another vehicle then I would remove and send them out for rebuild.

 

Swap the coil packs and see if it moved.

 

If you decide to replace the fuel injectors buy a new set. JMHO

https://www.fiveomotorsport.com/199...999-04-tacoma-34l-6-cylinder-single-injector/

 

I went through all this before as well. I replaced the plugs, wires and coils packs and boots with all OEM. Still had misfire. I have a friend at a Toyota dealer and they advised to check the compression just to make sure there werent bigger problems. That checked out fine. I had new fuel injectors installed and problem is gone. All this about 40k ago when my truck had 212k on it. 257k on it now and it purrs, I drive it almost every day.

 

OK! I'll do injectors and valve cover gaskets all together then. I'll do it in September.
With that in mind I've seen this thread before:
Injector PSA: V6 3.4L 5vz-fe 1st gens | Tacoma World
Where FRgeoff says you can use these:
Lexus Toyota RX300 Avalon Highlander Camry Injector 23250-20020 (S6)
Lexus Toyota RX300 Avalon Highlander Camry Injector 23250-0A010 (S6)
or the denso fuel injectors like these:
Enhance Performance and Reliability with 5VZ-FE Fuel Injectors | MotorWest Performance
So I'm curious if anyone has any thoughts on this route for fuel injectors? I want good parts for my taco but I also don't want to just break bank in the name of OEM when I could get the same product if not a better one for a much nicer price. Just like getting the denso coils and wires instead of Toyota OEM ones when they are basically the same.

 

When complete come back and let us know the outcome.

 

From your links it looks like the injectors from MotorWest Performance is the way to go especially with the lifetime warranty.
I'm currently going through this with a misfire in cylinder 1 so your info above has come at the right time!

 

Go with MotorWest