This is on my aunt's 16' Toyota Avalon, 66k miles. For 2-1/2 to 3 years it has made a nasty rotten egg sulfur smell after a hard acceleration. Nauseating, it gases you out and you've got to roll all the windows down for 5 minutes after to make it somewhat habitable. If you drive the car like an old lady, it's fine. Merging into the carpool lane, a fast highway on-ramp, or climbing the hills is what triggers it. 2-1/2 years ago we took it out of town to visit family and were gassed out. That was the last time it left the city, we always take my car or ride with someone else since then. When it was new we took it on a 2 week, 9 state, 5,000 mile road trip with 5 national parks. No smells. Plenty of full throttle runs.
We took it to the dealer 2-1/2 years ago and they thought it was the battery (it was leaking) so they replaced it. That didn't make a difference. Not wanting to deal with the dealer, she hasn't taken it back until last week. They can't find anything wrong, no pending codes, nothing under the car that's burning etc. They keep saying all they see that causes smells is bad batteries, but I replaced it last week because it died (AZ heat).
I think it's a bad catalytic converter, but the dealer says it can't be bad without a CEL
. They said they can't do more diagnostic unless she paid by the hour for them to keep looking.
Car also has an extended warranty until 120k miles, but I don't know that it will cover emissions equipment (if that is the problem).
Any ideas?