Interesting 1GFRE Injector issue

Having a odd miss at around 1000 rpm in second gear, I pulled the injectors to have a look and one of the injectors was different than the others. as shown.
Clearly it's carbon. the question is , where is the carbon coming from, and why just on one injector???
to me to have carbon at this point you have to have combustion very closeby (if not directly on) the injector.
any ideas?
see attached pics of sooty injector head x1 and clean injectors x5 (1+5=6 cyls)

 

Odd that you would go directly to the injectors over spark plugs of vacuum problem.

It appears that the orifice plate is fine with the exception of a slight bit of soot or whatever. None of the holes are blocked or dirty etc... As long as that is all you have it shouldn't be effecting the operation of the injector. How many miles on that engine? I've seen worse looking new injectors.

Where is the carbon coming from? Well every gasoline engine I have ever seen has a carbon coating behind the valves in the intake.

If you are really concerned about it run some Techron fuel system cleaner through it in the gasoline...

 

oh yes, I've done a lot to try to find this over the last 2 years to wit: did vacuum test, new plugs, all 6 new coils, new MAF, new o2 sensors, new fuel pressure regulator, fuel pressure gauge (Tacoma has no fuel pressure sensor nor filter, just the sock thing), new air filter, new throttle body, new quick attach fuel lines, new battery (ya.. new battery, old was was 7 years old anyway, why not), new fuel rail, compression test... (bought leak down tester, will do that soon).. oh and new intake gaskets. (the coated metal ones).. sounds like a lot but working on this engine particularly easy.. one 10mm socket and one 12mm socket and you basically have it all apart in 30 min.

But getting back to the topic, it's obvious from the holes that the gas is actually "Cleaning" away the carbon from the head, that you can see by the pressure jets pattern.. that means to me that the carbon source coming from another source other than directly from the fuel.. something special is happening in this cylinder, I just don't understand exactly what it is yet.

 

Move that injector to a different cylinder and see if your concern follows the injector or stays with a specific cylinder.

 

Excellent advice. Also, does the spark plug from that cylinder look any different than the other 5? Have you bore scoped that cylinder through the spark plug hole? How much oil are you burning between oil changes?