Since new, the RX takes a very long time (over 5 minutes) to get below 1000 rpms during warm up. I find it strange that it does that. I also got a vehicle that is D4S 4 cylinder that takes under 2 minutes to get below 1000 rpm.

How long does your RX takes to go below 1000 rpm during cold start?

 

Interesting question. It sounds like you are starting and idling your RX in the driveway. I almost never do that. After i start mine up Im driving down the road and never notice when idle speed normalizes after cold start. But, in an attempt to answer your question engine warm up time is a function of ambient outside temperature and operating engine RPMs.

 

Agree with Lex. I idle mine long enough to back out of the garage and driveway. Then I'm off on the road.

 

No way it should take five minutes regardless of outside temp. Less than one minute is probably reasonable.

 

My 2017 RX 350 takes about 5 - 6 minutes also. Not much different then all my previous vehicles. I start it up then wait about 30 seconds for the oil to circulate throughout the engine, put it in gear and drive off.

 

You would think it is temperature related but no. It happens during summer also. Even after the vehicle has driven for over 30 minutes, parked, come out and start it still takes a long time to get down below 1000 rpm. I just really find it strange.

 

Probably a computer-controlled function, same as the rest of the engine functions.

 

Do a simple test. When the engine is completely warmed up, say for 20 or 30 minutes of driving, park the car, turn the engine off. Wait 2 minutes then start it and see if the idle goes above 1000 rpm. If it does, then it is a computer issue like dibl says in previous post.

 

Well ... hmmmm ... What if the computer is using a thermal sensor on (or in) the engine as one of its inputs for setting the fuel-air mix and timing? If that is the case, after 2 minutes I would expect it to settle right back to ~700 rpm as soon as it restarts.

 

What if Mars crashes into the Earth next week? Then what? I was just suggesting a simple test. Try it and see what happens.

 

OK, I did. 2018 F Sport with 49K miles on it.

Car was cold in my garage at approximately 45F temperature. Outdoors ambient temp was 31F. Upon starting, car idled at about 1200 rpm. Drove through my residential area at 25 mph, pulled out onto a main street and drove at about 40 mph to my first stop in about 6 minutes. Idle there was still 1200 rpm. Drove a short distance to my second stop and while idling there, at the 10 minute point it dropped to about 700 rpm. Drove home and parked in the driveway, car was fully warmed up, idling at 700 rpm. Shut it off and waited 2 minutes. Started it and it went immediately to idling at 700 rpm. Put in the garage and shut it off.

 

My experience was almost identical except the outdoor and garage temps was 44F and the idle dropped to 700 rpm when I parked and shut it off at the 6-minute mark.

Started the car again 35 minutes later and it idled at 700 RPM.

2022 F-Sport 5,400 miles

 

I was asking the original poster of the thread to try the test. Not you dibl. Post # 8 Good grief. Give people a chance.

 

Thank you.

For me cold or warm it does not matter to my RX. Cold start at idle always takes a very long time to idle below 1000 rpms in Park.

On the other hand, once in drive and driven the idle will go below 1000 rpms in Park or in Drive.

After the drive in the summer. Restart the engine and it would still be over 1000 rpms at idle in Park for a while. These vehicles does not have an IACV so no idea why the high idle.

My purpose if this thread to see if anyone having similar issue like mines to see if it is normal as I have never seen any car that takes a long time to get the idle to go down.

 

I have the same exact model as yours. How long does it take your vehicle during a cold start to get down below 1000 rpms in Park in the mornings?