Have you tried pushing the A button next to the shifter to disable the engine from shutting down when you stop. Forget what it is exactly called but when the engine shuts down and you press on the gas to go there is sometimes a hesitation. When i start out i always press the A button to keep the engine from shutting off. This funtion is supposed to save on gas mileage. But it also puts wear and tear on your starter.

 

If you read my first post you would see that I stated I ALWAYS turn off the auto shut off feature. I have also tried leaving it in sport mode with no real difference. I NEVER run it in eco mode, just normal mode.

Very frustrated with this problem, I expected better from Lexus. In all the cars that I have owned I have never had this problem, reminds me of the old days with having a car with a carburetor.

 

I have the same issue with my 22 F-Sport. Temps at 90 or over with the A/C running. Turbo lags for a good 2-3 seconds from a dead stop. Dealer also told me they couldn't replicate the problem when I brought it up over a year ago.

 

These are the issues faced with a turbo engine when first introduced on a new model. BMW went through this and it was determined to be a faulty fuel pumps. They were creating lag and eventually would fail and had to be replaced. BMW finally re designed the fuel pump and things improved greatly. This was back in 2009-2012.

I personally prefer non turbo vehicles such as inline 6 or V6 engines. The IS 350 is the last of the straight 6”s without any turbo.

However all manufacturers are now going turbo. The IS will surely follow in this direction on next update.

It’s possible the NX may just need a software update to fix this lag. Yet without other owners having the same issue coming forward the fix may take longer to get resolved.

 

Just mainly out of curiosity, does the issue manifest differently based on the amount of time stopped? Does it matter if the car is stopped for just a mere instant (like at a stop sign intersection), or does it occur after sitting at a red light for several seconds too , or no pattern?

 

I never timed it but it seems if the car is hot and the air temp is around 90, the problem will show up. I would say the car has to be turned off for at least 5 minutes but I can also have the problem show up if I am driving the car real hard on a hot day. I always have the auto start turned off so I doubt the problem will show up if the car is only off for a minute but I haven't confirmed this.
We have cooler weather in Florida now so I will see if the problem goes away. If so, the car should be fine for the next six months with cooler weather and I will deal with it again next summer. Hopefully enough people will complain about it by that time and Lexus might have a fix for it.

John

 

Thx for the follow up, interesting. Reason I asked about the stop duration, I have been wondering if the issue is a physical one (induced by heat? or other) vs a software issue where things might change due to minor action changes. But if it is indeed heat related, that may explain why I haven't seen anything like it. My area was probably the only part of the entire northern hemisphere this summer that actually had somewhat of a mild pleasant summer. I think we approached 32C (~90F) just a couple times and most of our summer was floating around 25C (80F) for daily highs. I think I used the AC maybe 5 days total (I hate AC and will open windows until it becomes too much- winter is long in Canada, I don't need a reminder taste in the middle of summer).

 

So the hot weather has returned to Florida now and so has the hesitation with my 2022 NX-350. I did not have the problem once in the past 6 months with the cooler weather but now that we have had some days with the temp around 90 degrees the hesitation is back.
Same conditions as I described before so I will set a appointment with the dealer again and this time take them for a test ride with me driving to show them the problem. I was hoping someone else on this forum found a solution to this problem but no updates to the post since last fall. I love the car but can't stand this problem, I hope someone can figure it out and fix it.

John

 

@Tinkertech hit the nail on the head, there is a problem but Lexus doesn't have a fix. It a appears to be a combination of turbo lag and hot engine/hot ambient temperature. Something is wrong with their ECU since it has a programming flaw under these specific conditions. For the time being, be very careful when you live in a hot climate, have warm engine and have a turbo ( 350 ) . Sorry, you have to undergo this. hopefully Lexus will come out with a TSV soon and develop a fix for this issue, If you do get a TSB notice, either in the mail or through your phone app, make sure to address it promptly.

Good Luck and hope you time to a solution from Lexus is short.


YMMV,
MidCow3

 

See also my post #24

IMHO I think you input air ( ambient air is too hot) and the sensors on the turbo are incorrectly trying to compress (turbo) the air. I not sure if the sensor pressure is based on temperature or not. But just for speculation assume that het is the sensor indicator of pressure, and when you compress air in the turbo the compressed air is hotter ( this part is a principle of physics) and the sensor thinks the air is more compressed than it is so the nix is wrong and you get the initial hesitation.

Okay now a possible solution, cold air intake, This basically get air that is farther away from your engine and is cooler. This could possibly solve your hesitation problem and also add a couple of horsepower to your engine. I have used cold air intake on an Integra GSR and it made a significant difference in performance; granted the GSR is not a turbo ,but I think it would work on a turbo also.

There are cold air intakes available for the NX350 Here is one site, but there are many others: https://afepower.com/suv/import/toyo...50-22-23-nx350

Good Luck and don't hesitate

YMMV,
MidCow3

 

I never have understood why these devices are called cold air intakes. How does the temperature of the air drawn from inside the engine bay with a CAI (air heated from flowing thru the rads) be less than fresh air drawn in from a short duct from the front grill instead. I can see the filters used on these devices being less restrictive, but cooler air, how?

The NX350 has a liquid intercooler which is supposed to cool the compressed intake air. In theory anyway...

 

It might have something to do with the transmission, especially how it kicks in from a standstill. It could just be how the car's built, or it might be a sign that something's up with the transmission.

 

??? okay a little father away, maybe less restrictive air filters ? - but, here is what they say :


A cold air intake (CAI) is named for its purpose of bringing cooler air into a car's engine and combustion chamber. Cold air is denser than hot air, so it contains more oxygen in the same volume. This means that more oxygen flows into the combustion chamber, which increases the amount of fuel for combustion and results in more power for the vehicle.


... and POC ( proof of concept) , it made a significant difference on an Acura Integra GSR, much higher performance.

Anyway, maybe the NX liquid intercoolers are not that effective. ... remember the liquid cooled 3090 mainframes

Peace and Goodwill ( for my favorite forum follower )

YMMV,
MidCow3

 

Yep, cold air intake solves the problem

 

This just happened to me today after letting my car sit for a few days with the high temperatures (I’m in Florida). Had a very scary situation where I was taking an unprotected left and the car just stumbled like it was stalling or slipped into the wrong gear. I’m thinking about taking mine to the dealership to have them look, but I’m not very hopeful that they will find something. Did you end up taking yours back to the dealer? It’s supposed to be cooler temperatures the next few days.