Idles high when engine is cold.

My 2000 4 runner idles at 1800 RPM when cold. Idles at 800-900 when warm with A/C off. I have no codes on engine and passed California smog. Any ideas what’s wrong? Thanks Dave

 

I'm a 5th gen guy but that sounds like a pretty normal thing to me.

 

5th gen here as well and that sounds like very normal engine behavior.

 

Engines idle high when cold. It's basically the "warm up" RPM. Once it's warm the PCM, the control module tells it to settle down. High(er) RPM to warm up, then lowers. It's normal.

 

What is the cold temperature when it is 1800 rpm.
I too think 1200 to 1300 rpm would seem reasonable.
Have you cleaned throttle body or run a couple tank fulls of Techron recently?

 

1800 *might* be slightly high but not much. every vehicle I've ever had goes over 1k on start up, more so when it's cold.

 

The transmission will hold the lower gear longer too, If its real cold.

 

Thats to get the oil pressure up on a cold start. Another reason why they last so long.

 

Thanks for all the information. I live in San Diego and have owned this 4 runner for 18 years. It was normal for the car to start and remain at 1200 rpm’s for say 30 seconds and the reduced to 8-900 rpm with the engine temperature gauge at cold. Now it stays at 1800 until the engine temperature gage normal. It’s harder to stop at the first few red lights now. Something happened to have it at 1800 rpm.

 

1800 isn't normal for cold idle.

And for sure not until its at operating temp. I'm going to guess something on the emission side which is happy once warm.

 

That would be vaccum related? I found a split hose at one of the intake connections? If braking is a problem I would take it in asap?

 

I definitely don’t know everything but most these post are very helpful. The high idol is due to cooling. This vehicle uses a “HO2” sensor. Which causes the vehicle to ramp up the RPMs so the coolant can flow and heat up to operating temp faster. Completely normal. If anything clean the O2 sensor or replace it and the idol should go down slightly. Hope this helps.

 

Any idea if it’s the upstream or downstream? Thanks

 

How old is the thermostat?
Its design when new is to be closed when cold, then open up gradually as coolant warms up. At operating temp it should be open.
They do wear out and are sluggish to change flow. Eventually the thermostat valve does not move much at all.

 

always start with the basics. Clean the throttle body plate as someone else recommended. Did this just start happening? I agree with others who say this isnt normal, thats too high. But start with basics, if you havent cleaned your throttle body plate (super easy to do) Id start there. Might be as simple as an $8 fix. Either way you need to clean that periodically. There are good videos on how to do it.
https://www.youtube.com/watch?v=yWcgFUvkLMw

 

My 2000 did this on occasion but all I needed to do was to lightly tap the accelerator pedal after 30 secs and the engine would ramp down to the 1200-1400 rpm range for another minute then down to 700-800 rpm’s. Turns out I had a malfunctioning IAC.