This is the way it works........
Didn't read all the posts, but #21 on page 3 pretty much sums the whole thing up.
What happens is you have a front and rear oxygen sensor. The front one (pre-cat) measures the amount of excess fuel/oxygen left over in the cylinders when leaving the engine. The front (pre-cat) 02 sensor switches from about 200 mv to around 800-900 mv during every fuel injector pulse width.. This is how your engine (along with MANY other variables) decides to add more fuel to the combustion chamber or take fuel away to give an ideal 14.7:1 A/F ratio.. Your rear 02 sensor (post-cat) is NOT suppossed to switch from a low mv to a high mv during injector pulse width. The JOB for the cat is to take the pollution that comes out of the exhaust (I'm not sure which ones, NOx I think) and thru a chemical process convert them into non ozone depleting atoms..
Now here's the problem. Different manufacturers use different materials to acheive the same result. Japanese manufacturers in particulaur have cheaped out due to the VERY, VERY expensive materials required to acheive this process. It's also likely that their R&D team uses a different fuel than what's available in the U.S. therefore not having the issue during R&D.
One would smell this more during WOT since the vehicle goes into open loop and the PCM dumps in extra unburn fuel into the combustion chamber and ultimately out of the exhaust.
Another problem is that the manufacturers have to by LAW warranty the cat for 8/80 and they are ery expensive to build. Manufacturers would much rather set their PCM's up to not set the code unless the cat is just out of federal specs.
The only real option is to
1.) Have manufacturers build their cats with different materials which are in the long term worse to the environment than the issue it's trying to solve. It is also very costly to build them right.
2.)Have manufacturers run their vehicles slightly leaner during WOT acceleration, which is harmfull to the engine.
3.)Remove the sulfer from the fuel.
I've seen this problem especially with Japanese vehicles quite a bit. Typically it occurs with v6 and larger foreign cars. Mitsubishi also has this problem.
I've had to replace a few faulty catalytic converters and I'll be the first to tell you they are NOT cheap..
There is a huge black market for these things. No one wants the cheap aftermarket ones, but the OEM domestic ones sell for $200-$300 EACH on the black market. I know guys who work at auto dealers in the big cities. I've heard first hand how they've seen 12-13 trucks come in all in the same day around Christmas time with their catalytic converters cut off.
This is what happens. Your typical lowlife gets himself a hacksaw and a creeper. Rolls under a bunch of trucks and steals the cats. He then sells them to companies who troll the country looking for OEM cats. Othen times buying tens of thousands of dollars worth of cats at a time. He then sells them to India and other developing or third world countries where they don't care about their health. They then melt them down, take the ery expensive precious metals out of them, turn them into jewelry and ship them back to the US to be sold. Most likely Toyota doesn't put as many of these essential "precious metels" into their cats.
There is another solution I've read about above. As stated the rear 02 (post cat) is just a "catalyst monitoring" sensor. It in NO WAY effects the drieability or fuel trims of the engine. The ONLY thing the cat does is rob power and remove o-zone depleting atoms or whatever from the exhaust. The ONLY thing the rear 02 does is monitor the cats efficiency. That being said as stated preiously the cat could be remoed and a rear 02 "simulator" can be installed. The cat being removed will take care of the smell and the 02 simulator will simply keep your SES light from turning on... That is unless of course you are required to do a emission test every year.
Another idea would be to go and get one of those el-cheapo cats from autozone installed. I'm not sure if they work good enough to keep the SES light off or if they have the sulfer smell though. You could then put your OEM cats on ebay and someone from the blackmarket would most likely buy them up. (This is if OEM Toyota cats are wanted in the black market.)