Brand new owner to 2023 ES300h Ultra. I love this vehicle.

I did have one question about morning starts. If I start the car and sit long enough for the motor to kick in for warmup I notice that the engine runs noticeably rough for 1-2 minutes until up to temp. I don't normally do this but I was sitting in it for 15 minutes playing with the settings when the engine came on and I noticed it. Its not bad but I can definitely feel the vibration in the cabin. I tested it again this morning, as I reversed out the engine started so i just sat there in neutral for a few seconds to observe. Its odd, it doesn't continually run rough but has "pulses" of roughness.

I am well aware that these engines have been designed to get up to operating temp ASAP, which might include running overly lean all in the interest of generating heat. Of course once its up to operating temp the issue is gone.

Is this normal or a sign of something that might be slightly off?

 

“Normal”. All A25A-FXS do that.

 

It can pulse and rumble around at times. For truly vibration free experience, try EV some day.

 

Have you managed to reach any conclusions?

 

Yeah I haven't thought about this since I originally posted. By all accounts the A25A-FXS C is an amazing engine but it does idle a bit roughly when cold. No clue exactly why but I know there is a ton of technology on the cooling system to restrict cooling from the block to ensure that it gets up to temp as quickly as possible and I think the outcome of that is it can run a little rough when cold. At this point I could care less, I'm reliably getting 50 MPG and if the only downfall is a little rough idle when cold, I can deal with it. Honestly don't even notice it anymore. I think it was just my initial impression that it was a Lexus and it should be smooth as silk always. But I will take it!

 

thanks! To be honest, I feel a bit better knowing that this is probably expected behavior.

if this is how the engine is supposed to work, then so be it