Please direct me to the threads pertaining to the intermittent difficult cold starting of 2009 and older GR V6 4Runners.

My 4runner cranks for 5-6+ seconds before starting in cold weather. Ideas?

2008 4runner Serious Cold Start Issues

Cold start issue

Trouble on cold starts

Hey, thanks. Yeah, it starts fine first thing in the morning. After sitting for nine hours after work, it cranks a lot and sputters to start (long enough that I took a look at the tailpipe and there was some black puffs while starting). Makes zero sense. Always starts right up when warm. Only 66,000 km. Bought brand new. Always synthetic 5W30, always 91 octane. New Toyota replacement battery. Correct Denso spark plugs. Runs mint. Lots of power. Will peel out in 2WD with the traction control off. No check engine light ever in the last 11 years. And it's been 30+C all month so it's not a seasonal thing. It's been happening for the last 4-5 years and didn't think much of it but recently it's become more pronounced.

Hey Mike, One thing to take a look at. Fuse #4 in the dash fuse box is called a starter signal fuse. I'm not 100% sure on Toyotas but on some other brands, notably Nissan, this circuit tells the ECU to provide extra enrichment and timing advance during cranking to help with startup. I've found the fuse missing and/or blown on numerous Nissan vehicles when I worked at the Nissan dealer. Also, there can be a fault in the ignition switch that prevents current from flowing to this circuit. To test this properly; find the #4 fuse. Using a test light, check for power on both sides of the fuse while cranking the engine. It should only have power when the key is in the start position. If both sides have power, this isn't your problem. If only one side has power, the fuse is blown. If neither side has power while cranking, you've likely got a bad ignition switch or a fault in the circuit. Hope this helps.
This youtube video can show you where fuse #4 is located. Fuse box location and diagrams: Toyota 4Runner (2003-2009) - YouTube

Since you say it starts fine first thing in the morning but not after sitting for a few hours and you see black smoke coming from the exhaust while trying to start it, I'm guessing that some of the fuel injectors are worn out and leaking fuel into the cylinders after you shut it off and causing the engine to be "flooded", i.e. the fuel to air mixture has too much fuel which cannot ignite.

You can do a simple check to see if this is a possibility, when you are having this issue and it's not wanting to start, after the initial attempt turn off the ignition and go and get close to the exhaust pipe and see if it smells of raw gasoline, if so this maybe the problem.

Thanks fellas. Leaking injectors was the first thing to cross my mind. Only thing is, why would they leak only some of the time/only under specific conditions. The problem isn't bad enough to warrant tearing into the engine just yet. Again, only 42,000 original miles. To be fair, this truck is mostly driven short trips around town. I gave it an Italian tune-up two weekends ago so I do air it out periodically. I guess I'll just have to wait until something more obvious happens. Otherwise, it runs perfect.

Injectors just don't go bad all of a sudden, it will happen over time and sporadically, and just get worst over time as the seals deteriorate more.

The next time you have the issue try the exhaust sniff test I suggested, if it smell strongly of gas the issue is definitely a flooding issue and the injectors would be my first thing to check.

Ok, so I totally misread the OP's problem. The diagnosis I spoke of above is for a vehicle that is hard to start the first time each day. If it starts fine cold early morning, but is hard to restart after a hot soak, then I concur with Auseeker. Leaky injector(s) is the most likely culprit. Also, OP I know you said it's not bad enough for you to worry about yet but please keep in mind that some of that leaking fuel can make its way past the rings and into the oil pan, diluting your oil. I'd at least smell the oil on the dipstick periodically. Fuel contaminated oil will destroy your engine in a short time.

I stated up top that I saw puffs of black smoke when it happened so I don't need to sniff when my eyeballs work fine. I wouldn't go so far to say it's flooded but it's definitely really rich. I got a better idea. Tomorrow after leaving work, I'm gonna crank it a bit while holding the accelerator to the floor before starting it. If it starts normally after, then indeed it's a flooding issue. We'll see.

It starts FINE, every time, after a "hot soak".

Again:

Starts normally after sitting overnight;

I drive to work;

It sits for nine hours;

It cranks longer than normal and sputters A BIT but starts and runs MINT;

Fires right up with zero issues even HOT (it's been in the 80s and 90s recently).

WELL OK there Mike, many people don't know what "puffs of black smoke" means, I had thought you were looking for opinions on what the issue could be, Importman and I were only trying to help you....but it appears you know all you need to know without our opinions....good luck on your issue!

Thank you so much for all your help.

So it stopped doing it. The ONLY change is I drive to work in the afternoon and go home close to midnight.

It's a puzzling, intermittent issue that has gone away for now.

Also, on a side note, I took off my catalytic converter heat shield and cleaned out the rusty crap that was rattling and buzzing. Put every back together with stainless hardware. Nice and quiet again.