Hi, just bought a used 2013 IS250 AWD couple of weeks ago. First post here. I've been lurking here for couple of weeks already. Great information and nice friendly members. Look forward to contributing in the future. For now, I have a question and hopefully this has not been covered in other posts already. Everything seems to be ok with the car except for 1 thing: The idle. I know it's normal that the engine revs at a higher RPM before it reaches the normal operating temperature. But whenever I come to a complete stop (again, before it reaches normal temperature), the rpm would dip momentarily to about 800 rpm and then inches up to 1000 rpm. When it does that, the car would lurch forward requiring me to apply the break harder to avoid hitting the car in front of me.

It would eventually stop doing that and stay at 700-800 rpm after reaching normal temperature. None of my other cars do that. I brought it back to the dealer last week for this issue and they said it's normal. They plugged it into the diagnostics tool and no error codes were returned and they claimed everything appears to be running at optimal levels.

Before I declare that they are blowing smoke up my behind, I'd like to see if anyone here had similar experience with their ride? Given Lexus' reputation on quality, I seriously doubt this is by design. Thanks in advance for any helpful comments or suggestions on what it could be. I see some posts about carbon build up after doing a search but not sure if this is related issue?

Lexus73

 

Yes it is normal. All my previous cars have done this regardless of brand.

 

They gave me a 2016 is250 as a loaner and it did not exhibit that behavior. I mean the idle will still inch up before engine is warm but not to the point that it requires me to apply the break harder to prevent it from ludging forward.

 

mine 2010 is250awd bought it cpo back then in 2012 and does the same, did research and its normal, only occurs in winter season while hvac is on, rpm will be back to normal once optimal temp is reached. (600)

my 08 altima 2.5 bought it brand new back then never had this issue though.

 

Seems normal to me. My 350 does the same thing when it's cold out, little bit more pronounced when it's extremely cold, for example, I left Chicago about 3 weeks ago and it drove like that every day until it warmed up to operating temp. Just the nature of these engines I guess.

 

Try and shut the air system (HVAC) off. You will notice it won't rev as much...

Strange I know. Where I live we have harsh winters (0F to -5F (-20C to -30C average)) and man this is very annoying on cold days, especially that I don't live far from work so car doesn't heat to operating temp before I reach destination. Idle is crazy.

You are right, I also had a 2015 IS250 loaner which didn't do that. I think it's a common issue for 2IS (2nd generation). IS owners living down south won't know what we are talking about

Our cars are reving that high to help warm the engine, especially when you put the heat on, engine temp tend to decrease when heat is on. Since inside air is heated by the coolant itself, cold air from outside is also cooling down the coolant being warmed at the same time, which increase the idle. That's why they tell you to put the heat on full blast when your car is overheating.

Clearly one of the downside of my IS... (with the backseat legroom issue, of course)

 

What you're noticing is the transmission and mainly its fluid. The thicker fluid in its cooler state is engaging the plates insides inside the trans ever so slightly more than normal causing the vehicle to want to move forward even with the brakes applied 50% at a complete stop. Until the outside temps or the internal trans fluid temps increase to normal, you'll notice this.

Completely normal for every auto vehicle I've given in the winter.

 

Thanks for all the input. I still don't think it's as smooth as it could be...especially for a Lexus. I've lived in Chicago for over 30 years and driven many vehicles through our punishing winters here but never encountered this behavior in any of them. I'm just glad it's not an isolated issue for my car then.

Lexus73

 

It's a factory setting to idle higher until optimum tempeture is reached. I believe it does this at any tempeture below 38 degrees.

 

It's not the issue OP is explaining. 2nd gen IS's idle increase dramatically when engine is not fully warmed and when you turn on the HVAC, transmission engaged or not.

I know idle increases when engine is cold to help reach operating temp, but 2IS are really intense for that. It was, by far, less noticeable in all of the others cars I've owned.

 

It won't get smoother trust me... I shut my HVAC off when I'm in traffic and engine is not warm... Really bad I know, but that high idling is too annoying for me so I endure the cold lol.

My temp gauge is at 1/4 warm (supposed to be somewhere in the middle) and the idle is still at 1500RPM when heat is on lol

 

I was explaining the "issue" regarding his following statement :

"the car would lurch forward requiring me to apply the break harder to avoid hitting the car in front of me."

Didn't care to comment on the idle issue as many had already.