Fluctuating RPM

[DenverDave]

After the engine is warmed up and in idle the RPM continuously cycles between 400 and 600. It will be running smooth at 600, then the RPM drops to 400, where it runs rough for a few seconds, then the RPM increases to 600 where it runs smooth for a few seconds, etc. It has done this since the car was new. Is this normal?

[Parmas]

What engine do you own?

Could you set the idling to 800-1000. 600rpm seems too low for me

" It has done this since the car was new " Why don't you ask the dealer that sold you the car in the first place?

[TheSilkySmooth]

It does this when charging or under load with heater/ ac or radio headlifghts. Normal but suboptimal. AFIK nothing correctable.

[PHXDEMON]

It's just how toyota tunes these cars to get as much gas mileage as possible. It is normal.

[schleppy]

Normal, mine does it too from time to time.

[DenverDave]

OK, I thought it could be normal. It's like the engine is seeking to burn as little gas as possible.

[yaris2010RS]

i have posted a similar problem also. mine idles at 500 rpm then will jump to 800rpm (ish) and then drop down. at first thought it was the a/c kicking in so i turned everything off and it still does it. look under the hood and watch, i noticed as soon as it jumps up the rpm the fan will kick in and when it goes back down the fan turns off.....

[TheSilkySmooth]

Operating with any partial or Defrost On setting on air director with fan at 1 or higher = AC on; regardless of ac switch on or not. I think.

[blacksandiegovitz]

It does this when charging or under load with heater/ ac or radio headlifghts. Normal but suboptimal. AFIK nothing correctable.

^^ +2

[why?]

mine has always done it. it's normal.

[sk8manmike]

Mine does this too - exactly how u say. Stays at 600 and then drops to sub 500 rpms, except my car shutters slightly when it does this. Should I up my idle rpm to say, 700?

Nvm i guess you can't since its electronic - guess i just have to live with it :(