Idle Air Control Valve

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Not sure if the car has one or not being an 05 Toyota Matrix. The mechanic took off the throttle body for cleaning and he said it didn't have one. But just one to be sure since it has a high idle on start up. Right around 1800 or so and slow to come down off of that. Car has drive-by-wire which I think they went to in 05. Need to put in new spark plugs so maybe that has something to do with it. Thank you in advance.

Rock shows the part is available but Amazon part finder doesn't. I guess I can plug the vin into Toyota's parts store and see what comes up.
 
I think IAC valves disappeared when throttles became servo driven. No need for them when the computer controls the throttle directly. It's entirely possible there's an idle learn procedure that needs to be performed. I just had to remove the throttle body on the wife's Equinox and it reacted by idling high. The cleaning probably had something to do with that; if it builds up deposits near where the throttle rests, then cleaning them up effectively opens the throttle more. Once I did the procedure it behaved normally. The procedure on the Equinox was letting it idle for 3 minutes, turning the engine off for 60 seconds, then starting it again and letting it idle for 3 more minutes, but you may have to Google it for a Toyota.
 
In 2005 there was a mid year transition with the throttle body of both the Matrix and the Corolla. Depending on when bought determined which you received.
The " Drive by wire" design that you have means that there is no independent IAC valve. The idle is set via the ECM.
That being said, certain ECMs of that generation were recalled due to cracks in the circuit board. Reach out to Toyota Care with your VIN to be sure.
Finally, your issue with the high idle at startup most likely points to a leaky Intake Manifold Gasket. Common issue with this generation.
Ask me how I know.
grin.gif
 
Originally Posted by incognito_2u
Finally, your issue with the high idle at startup most likely points to a leaky Intake Manifold Gasket. Common issue with this generation.
Ask me how I know.
grin.gif



Thanks to everyone for the posts, very helpful.

I did have the IMG replaced with the updated orange gasket last October which solved the rough running when cold. This is more of just being loud from the high rpm. I think there may be an exhaust leak on top of the muffler or something. I had the car inspected by a good mechanic last December and he said the exhaust looked good. Including a repair I had done two years ago where the donut gasket in front of the cat. converter was replaced. So I think the high idle combined with a slight exhaust leak might be the culprit. I can take it back to the muffler shop which is pretty good. They are very busy and have great reviews. Small indy shop that's been around a long time.
 
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