I know this is normal for the first 5 to 10 min when car is first started in the colder mornings, but after complete antifreeze flush, now it takes more than 15 min before Idle is back to normal. This is kind of dangerous as I have to apply the brakes harder than usual at red lites to prevent the car from rolling forward.

I check antifreeze levels and bled the system a few times to get rid of any air, but still takes too long to idle to get back to normal until fully warm.

Car has 57K and year 2007 250 AWD

Any input is greatly appreciated .

Lou

 

Did you touch the thermostat at all? If it was removed, perhaps it was installed incorrectly, such as upside down?

I've never touched the coolant on my Lexus, so I am just throwing out some suggestions. Kind of sounds like the car isn't getting up to optimal temperature as quickly as it should, as if the thermostat is open when it should be closed.

 

Check you vehicle for any vacuum leaks.

Also check to see if your air intake tube is connected properly and tight.

It may be the thermostat sticking open and letting the coolant circulate in a continuous loop. A good way to test is start your car when it's cold and touch the top radiator hose. It will be cold to the touch until the thermostat opens to let the hot coolant into the radiator. See how long it takes or see if you feel coolant just flowing through it from start up.

Check the temperature sensor to see if it is working properly. It may not be telling your ECU that the engine is warm enough to reduce fuel and air.

Since you were doing a coolant flush you may have pulled a vacuum line somewhere and not noticed. Check it well.

 

Well. My 2008 IS350 high idles when the temp outside is 37 degrees or less so it can warm itself up. Yeah it takes a while, but that itself is normal

 

This is an old thread, but still relevant. My 2012 IS350 idles high, until it gets completely warmed up. I found that if the outdoor temperature, as displayed by the IS350, drops to 39F, it will start revving high at a stop sign and downshifts harshly. I recently found that if I turn the climate control fan off, the temperature, at which the high revving starts, drops to 30F. My commute to and from work is short; 7 minutes. So, I leave the fan off, if the temperature is <= 39F. I rely on the seat heater to provide some heat.

 

2013 350 is identical to this. I turn off the heat while stopped. Maybe next time disable AC and see if that helps? Crazy this car does this.... literally ramping up RPM at a stop after being stopped. Can be dangerous without enough brake applied.

FWIW Techstream shows like 60 options within the HVAC panel. There may be something to disable or change.