How do you change the idle air control valve on a 2001 Toyota Sienna?

Answer 1

You will need to access the underside of the throttle body, for my 2000 Avalon this meant:

Disconnect neg battery cable first. Next remove the air regulator with the intake hoses attached. The hoses may be somewhat stuck, but are made of a height quality rubber ($27 toy price for ONE), mine are 8 yrs old and were NOT brittle.

Then remove the engine cover (easy),disconnecting the pcv valve hose, throttle cables (easy), disconnecting several vacuum hoses (easy) and sensor plugs (easy, if you push the release) but then there are more hoses with slip rings on them that are difficult...the slip rings need small and angled needle nosed pliers to get the right angle to release them. Then, slipping the hose off it's connector requires strong fingers to free them for their connectors. That took the most time, patience and sometimes careful prying.

Once all that is done-90 minutes for me, there are 4 bolts for the throttle body that are medium easy to loosen with a metric wrench. The throttle body (TB) is now free to flip over, and access to the four screws attaching the iac to the TB is achieved...then comes the next big problem.

The screws require an exact fitting Philips screwdriver to remove...i have read some used an impact driver to remove it...others stripped the screwhead and used either a vise grip or the stripped bolt remover from Sears.

I gave it a try with my available Philips, saw that none of the screws budged, and decided to leave the iac on. Put the TB assembly back on right side up and over the next half hour squirted TB cleaner into the iac opening, letting it drip on to a rag i placed on the bottom of the iac. Also cleaned the TB ports with the cleaner and rag.

My problem was intermittent rough idle, stalled starts, possibly due to a sticking IAC.

The sticking is caused by oil vapor deposits on the IAC, i think it comes from the pcv valve, bec i found oil deposits iside the air regulator. Toyota service will recommend replacement at @ $200 for the part, plus labor.

So after my "cleaning" I replaced everything in reverse order, the hardest part is replacing the slip rings to the original positions, tested the startup and there was no rough idling at all.

It's only been one day, but others have not had their idle problems return after cleaning the IAC.