I currently have a 2012 RX450h. Whenever the car is restarted even after fully warmed up, the gas engine will always kick on briefly and shuts off, even if the hybrid battery has a good charge. I had a 2006 400h which behaved the same way. The way around that is if I go into the menu real quick upon starting and force EV mode, which of course only works if the engine is fully warmed.

Also have a CT200h, and the gas engine doesn't kick on if the car is warmed up, and I can force EV mode with a cold engine even after being parked overnight in the summer time. I test drove a UX250h recently and it behaves like the CT200h, gas engine doesn't kick on upon starting. My inlaws have a RAV4 hybrid and it behaves like the CT. I know I'm comparing apples and oranges, but I'm wondering how the 4th gen RX450h behaves when starting.

Bit of a strange question, I know. I just find it handy if I have the move the cars around in and out of the garage and driveway to not have the gas engine kick on. At least the 4th gen RXh has a direct EV button, whereas my 2012 3rd gen I'd have to go into the menu.

 

My 2017 has the gas engine kick on regardless of whether or not the engine is warmed up. If it is a cold start, it will automatically go to EV mode in about 2 minutes if on a good charge. If the engine is warmed up, it will start the engine for about 20 seconds then go back to EV mode. Engine starts about 5 seconds after powering on the car. Cannot force the car to EV mode, it will show EV mode unavailable.

 

Thank you. I suspected this would be the case. I am surprise though that you can't force EV mode upon restart on a fully warmed engine, which I can do in my 2012.

 

Now that I've had the car for a week, I learned that in order to force EV mode when restarting the car, the car mustn't have been shut off for more than a couple of minutes. Any longer and it gives the EV mode not available message. In the 2012, I was able to force EV mode with less restriction as long as the car is still warm. I really wonder why Lexus programmed it this way.

 

On the converse, should the engine always turn off when the car comes to a stop? If so how quickly does this occur, longer when the car is still below normal operating temperature?

I'd like to understand what the logic is for the transition from start to go and for running to stop.

thanks

 

Yes the engine always turns off within seconds of coming to a stop if the car is warmed up. The only exception I've seen in the 2012 was if the traction battery is completely full (or empty for that matter), it keeps the engine running at a stop. I'm not sure the purpose of running the engine when the battery is full. I live in a very hilly area and on my way out, regen can recharge the traction battery pretty quickly. I have not yet seen my 2019 reaching a full charge and the gas engine staying on because of it yet.

Still pretty early in my ownership, but the 2019 warms up noticeably quicker than the 2019. Within the first 1/2 mile of pulling out of my house, the temp needle is already past the first line on the temp gauge, and the car can soon go into EV mode while cruising in my neighborhood.

One odd bit when I filled up the car earlier this week. It was a very warm day and the car was of course fully warmed, having been driven for a while when I filled up. After refueling, as soon as I started the car, the engine kicked on for not even a second and shut off before I even shifted it out of park. It stayed in EV mode until I pulled out of the gas station.

 

The computer is very smart and will decide what's best for the engine and overall fuel economy. As for the engine "running" when the battery is full, it's not. The computer is telling the electric motor to spin the engine but with the fuel off, in order to consume excess battery charge. The engineers have figured out what the full and empty limits should be in order to get lifetime service out of the traction battery.

 

No, ICE does not always kick in at each start. I drove my HiHy for distance purely on motors after start up. Yiouy have to have feather light foot, that's for sure.
ICE WILL start if you have heat turned on. Or, if EVAP or cat are below required temp for proper operation. Battery charge state has none toi do with this as ICE is turned on primarily to warm up cat, EVAP and produce heat, if accelerator pedal is not requesting high power demand and hybrid battery is above 2 bars charge.
I could drive 4 floors up in my garage on electricity only after start up.

 

I figured that's what it does, but I didn't know it actually shuts off the fuel supply.

 

In the RX450h it does (same with the 2006 400h I had but that does not have the ability to force EV at all), however briefly, unless conditions allow for me to force EV mode and I actually get to it before the ICE starts, which in the 2012 involves going into the menu on the steering wheel so I had to be quick. Now that I have a direct button in the 2019, it seems it's even more restricted that it was in the 2012. I've seen it give the message EV mode unavailable when I press the button, when the car had already put itself into EV mode lol. But yes I can drive the car out of my community without the ICE as long as I control the throttle, which is easier to do in the 2019 than the 2012.

I really love that the CT200h, even after sitting couple of days, as long as it's not too cold out it allows me to put it into EV mode right away.

One of the reasons I brought this up is that because starting up the ICE when cold just for a few seconds to move the cars around is not the best thing for the engine, especially in the winter time. Doing so allows for excess unburnt fuel sitting in the cylinder, and the car will run very roughly and spew very heavy exhaust fumes on the next start.

 

Look, my HiHi power train was identical to what you have in RX. No difference. And I had 2 hybrids. They both behave exactly same - as I described. If hybrid battery is charged, cat and EVAP are warm, you are not requesting heat or slamming on gas pedal - ICE will NOT start. MOF, should you go in reverse, that's electric only anyway.
Either programming is wrong with your system or, you floor the gas pedal. Or, you do something else you are not telling us or not even aware of. happens.

 

Either something is different about your car, or all 3 of my (2006, 2012, and 2019) came with different/defective programming. My CT200h I can have it parked for 2 days, drive it out of my community and the ICE will not start as long as I modulate it properly. Having driven Lexus hybrids for well over 200k miles combined, I know how to work the system. *My* 3 RX hybrids will always start the ICE upon starting (however briefly) unless I intervene by forcing EV before it starts, (unavailable in the 2006 because it never had the EV button).

Edit: Wait, what car do you have? Highland Hybrid? Yeah I know they have the same power train. If the Highlander indeed does not start the ICE on each restart (if conditions allow for EV operation), that is a very curious difference between the two. I am telling you, even after a long drive, if I shut the car and restart it within a minute, the ICE will kick itself on briefly and shutoff. All 3 of the RX hybrids I owned are the same way.

 

'18 450h here. I've never had the ICE not start no matter how warm my engine is. No heat, A/C nor fan on either. I could leave the tranny in P and not do anything, and the ICE will kick in after about 5-10 sec on its own after startup. Sometimes it would just be a quick <1 second sputter, as if it's just lubricating the engine. After that, I can putter around in electric only mode for as much as the batteries can handle.

I've never tried pressing the EV button right after starting up though (on a warm engine).

 

Seems that all the non-starters described in this thread are 4 cyl. (1.8L CT's, 2.4L or 2.5L ES) and the
starters appear to all be V6's (3.3L RX400h's , 3.5L RX450's) Still would like to know why...

 

I have the towing package on my 450h, but I've noticed that the engine cools really, really quickly. My other car with similar engine size will warm the garage for hours.