00 Avalon - rough starting

[aquaman00]

Hi, I've got a 00 Avalon, 60Kmiles that has intermittent rough starting after cold starts only. Warm start seems to be ok.

The engine will crank fine, but as soon as it kicks over, it'll hesitate, sputter and sometimes die. Gassing it will get it out of that mode. Seems to happen most when it's hot outside or it has some ambient temperature dependency... No check engine lights.

The IAC appears to be clean, there's no EGR valve supposedly starting on the 00 model year.

It has new sparkplugs and air filter. Haven't replaced the gas filter, although the car runs and idles perfectly fine and smooth once it gets going.

Any suggestions on what else to check?

[toyomechanic421]

the iac valve may appear to be clean but it can still be bad. Avalons are notorious for their iac valves going bad. If your battery is good i can assure you that you need to replace your iac valve. When they go bad you cant always see it but tiny particles can cause them to stick. Thats what is happening, intead of the valve opening to allow a higher idle, it will stay in one place, not controling your idle at all. I am a dealership mechanic and see these problems daily. hope this helps.

[Brian R.]

I believe it is possible to clean the IAC valves if you are careful and use a high-quality cleaner solvent.

[csaxon]

Check out your air filter box and all the hoses from it to your throttle body. Look for poor sealing or air gaps or disconnected hoses. Press them up snuggly.