Lexura16

@Cookiemonster Since the Seafoam treatment gave you good results, you should continue this schedule and see if the improvements continues. I see no down side in following this regiment as long as you can detect improvements with its use.
I'm assuming that once the engine started ( from one to numerous attempts ) that the engine operated flawlessly ( normal ) at all throttle inputs.This makes it difficult to point to dirty/leaky injectors, pressure regulator, fuel filter, fuel pump in the fuel delivery system as prime culprit(s). Has anyone worked on the fuel delivery system and removed ( or forgot to reinstall) shielding around fuel line(s) near heat source(s) that could vaporize fuel and cause an airlock situation.

Cookiemonster

Nobody has worked on the above mentioned parts. I hope this issue doesn't come back.

LexMan2003

I have a 2020 NX with ~75k miles. Change my plugs every 35k and always use premium from same station. I throw a bottle of Techron into full tank appx. every 3 months. I regularly check my battery water level and top off with distilled water (if needed).
Perhaps 1 out of 80 starts it cranks for a long time, similar to what OP experienced. On second crank it starts right up.
I will check my battery water level this week.

Does this 1/80 bad starts sound similar to OP's issue? Should I consider having the fuel pump looked at by dealer just in case (I'm still under L/Certified warranty).

Thanks.

Cookiemonster

It doesn't sound the same. Seems like others are experiencing it quite consistently (every day).

Shields8

I have a 2021 NX, 60,000km in Calgary. Exact same problem. I had a spreadsheet of details when it was occurring, weather, drive times etc. Dealer was able to recreate it (had warranty is now out).

They found injector on cylinder 3 was leaking ( showed damp cylinder with a boroscope. They replaced that injector, was better for a month or so.

Problem started again. Showed fuel on the other 3 cylinders so they replaced those injectors. Figured maybe a bat batch. Lexus has a bulletin out about it allegedly. Dealer tech said they’ve seen lots coming out of Ontario.

Been 2 weeks and was good, but has started being ****ty again today. 3/3 starts today barely caught.

Cookiemonster

What do you plan on doing?

Shields8

Well I'm now out of warranty and the odds of 2 sets of bad injectors is slim. Going to start with changing fuel provider, and replace spark plugs.

From there, likely look at fuel pressure regulator. Before that, I might try opening my fuel tank when I park and relieving the pressure to see if its a system pressure thing and if that can relieve it. There is a little vacuum pump that runs and keeps something pressurized, so trying to figure out wtf that is, and where its keeping pressure.

Cookiemonster

If I may suggest trying Shell. I had slight improvement with using them instead of Costco.

I would also recommend trying fuel system cleaners because that really helped me and that was an affordable test.

I recently got an oil change and that seemed to have helped as well. I’m planning on going with 8k oil changes instead of the 16k manufacture recommendation.

Let me know if you find something that helps?