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Experiencing a problem with your car? Troubleshoot in here.
By Mr_Renfield
Car: AE111 Corolla
Engine: 4afe

Engine revs go up (~2100rpm) during idle.
When I start it in the morning it's fine. After a few kms the revs go up during idle.
It goes up even more when I come to a dead stop or when depressing clutch pedal.
Recently I tried to get the revs back down by using the aircon.
It actually worked, but today when I tried that the revs still stay high (tho @ 1400rpm).
I noticed the whole rev thing starts specifically at this one turn I take in the mornings.
Could it be related to the power steering?

I searched the forums but all I got was info on the 20v or that revs only go up during startup.
Mine is the opposite.
By Die$eL
check all the rubber piping around the throttle and air intake area.
could be a blocked/loose pipe.

also, check that the accelerator cable is not jamming or too tight
By Dev20V
Its also possible that your throttle body needs some cleaning.
It will start as normal in the morning but once you're driving and reach normal operation temp, thent it will rev up.

The throttle is getting stuck in the open position. Had this issue on my previous car.
Just clean it with some Carb cleaner and you good to go. :thumbright:
By Mr_Renfield
Ok I'm going to check out the throttle body.
I have cleaned it before, though that was to sort out a sticky throttle valve.

If it is the throttle, then it's strange that the aircon brings things back to normal.
Like when I switch on the aircon, the revs go back to normal, even after switching the aircon off again.

Does anyone know if the 2002 4afe has an ECU controlled ISCV?
Or is it the mechanical type?

After reading up a bit (EFI Course Book, Toyota Motor Sales, USA) I'm thinking it could also be the idle-up valve.
It's used to increase revs for full turn on powersteering and aircon use.
I think it's not closing properly.
By Mr_Renfield
Ok the revving thing went away (without me doing anything), but is back with a vengeance.
It's so bad now that there's no engine braking possible.
At high speed downhill (no throttle) the car even jerks once in a while. Like a hiccup.
Very scary. Like hitting a brick wall for a millisecond.

Will check rubber piping and clean throttle body.

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