All of these numbers and times are going to be different depending on how cold the engine/outside temperature is, whether or not you sit there letting it idle or start driving, and how you drive.

It's going to idle higher longer the colder it is. I wouldn't worry about it unless your fully warmed up idle is far off from 600 or jumps around a lot after that point.
That guy in Siberia has his idle at 4800 rpm for half an hour.

Remember this is the car trying to prepare itself for operation, when the fluids are cold in your car they are like thick sludges. They say that with modern cars "warming" up the engine isn't necessary, blah blah blah, but I still like to at least let it get it's first little fit out of the way and settle in around 1000 before driving off.

 

I am not sure why that is.

 

I couldn't agree with you more. My main question is the sudden spike about 5-10 second after startup. If it started off at 1800 rpm and then steadily dropped, then I would not have opened my mouth. It's the rather noticable spike that I not only see, but hear.

 

I'm pretty sure I've observed the same. I believe my 2ZZ-GE was even more pronounced with this effect sometimes shooting much higher up than that but not immediately (given it's redline was 8000 rpm, understandable I guess).

I can only guess at what the car is "thinking" when this happens, but perhaps it takes a little while to judge just how cold things are taking into account the air temperature as well. We need a toyota/lexus master tech on this forum to satisfy our curiosities.

In my case, it doesn't only just spike up, but it seems to reciprocate between the higher and lower rpms on the high range until it settles in sometimes.

 

Funny that you say that. I used to be a Toyota Master about 8 years ago and switched professions since. I still know a ton of them but don't know any lexus guys. I'll hit up one if my old co-workers who still wrenches and see what he says.

These cars have changed so much since I wrenched. Typically air temp really has no affect on idle speed. It's mostly done by coolant temp. Well, at least it used to.

 

You're probably right, it was just a shot in the dark. I've never wrenched for a living (I'm a software developer, not typically what people think of when they hear about somebody using hand tools) but I've done a lot of my own work on past crappy cars, and pretty much disassembled and reassembled my motorcycle on a couple of occasions (that thing has made me a lot less mod hungry, I think I got it all out of my system and realized just how much money I wasted!).

I guess it's a mystery for now.

 

still not seeing any jump here. car was outside office in the cold rain (newport beach) and was 47 degrees when i left office. started the car and just went up to 1500rpm and dropped from there

maybe i should go up to big bear now

 

For some reason, I figured you were in software. (Binary)

 

Go for it! Although not right now with this weather. Imagine the roads and your slammed car on those roads?

I'll take a video and post it to see what I mean.

 

Did you say cold Send some of that cold my way and I will send you some Chicago Style Cold

My car does this when its cold but doesnt do any kind of 2nd jump. I would say its maybe 1500 at most and it drops as it warms up like any newer car. When fully warm my car has always idled around 600.

 

Do fuel injected cars have "chokes" like old carburated cars? I always assumed that was what caused the RPM surging during cold startup.

 

I checked my car this morning and it doesn't do that. Sorry. It just stays on 1500

 

47 Degrees is like a nice spring morning.

 

lol i am sorry tony and i made you guys jealous

 

I love my city, but I do envy your winters sometimes. Our summers can get nearly as hot as yours, though.

The positive thing is that we have lots of fresh water, and don't get any earthquakes, hurricanes or really any other natural disasters apart from a good dumping of snow a few times a year. =)