That's exactly what I was going to do. Looks lean, I'd check the O2 sensor with a digital storage oscilloscope. Kalifornia states that the response time lean to rich should be under 100 milliseconds. In reality it should be in the 30-40 millisecond range. Any slower than that and it can't truely control fuel properly for best emissions.

BTW, running lean can burn out a catalyst almost as fast as running rich. More unburnt fuel (lean misfire) gets sent to the cat with extra O2 to make sure it burns well. To top it off, running lean means running hotter. The excess heat contributes to catalyst substrate degradation.

My suggestion is for you to take a hard look at that O2 sensor.

Thanks for the info. I put a new Denso O2 sensor on order through the local AutoZone. They can have it to me tomorrow. It cost a little more than online, of course, but I wont have to wait more than a day for shipping and I can return/warranty it at any AutoZone.

I don't normally throw money at things trying to fix them, but I think this is worth a shot. <img src="/forums/images/graemlins/cyclops.gif" alt="" />

The key to your problem is the cat.Whenever you get all three readings high its ALWAYS the cat.Aftermarket cats only have to be warantied for 2 years,so the amount of precoius metal is reduced from oem[hence the price].Im not sure what burned out constitutes.If you melted the substrate then you have a really rich problem,but if your cat simply ran out of catylyst,thats fairly normal.I once ran a cavalier on a dyno with a pulled plug wire,and it passed,albeit with high hc and co.NOX was fine because the unburned fuel cooled the combustion chamberand the converter evaporated it.Converters do make a helluva difference.Next time you think you have a cat problem use a infrared non contact thermometer and measure inlet and outlet temp.If the difference isnt at least 50 degrees[usually more like 100] the cat is dead.Just remeber,when all three gases are high,its ALMOST ALWAYS the converter.As far as your lean condition,put an o2 sensor in,but I wouldnt sweat it if it didnt change anything.Also,if the engine uses oil[like often happens after a valve job on a high mileage engine]that oil coats the internals of the converter and it wont work for long.

New cats are usually good for knocking HC's down by 300-400 ppm, normally if you are higherthan 400, a new cat wont get you low enough to pass.

By the looks of it, the stock cam made no difference at all. The measured difference in the numbers is more likely caused by the allowed tolerance of the smog machine, than the EB's cam.

I agree. The EB cam is definitely smogable.

one cat for smog?
one for street?

There are all kinds of environmental and ethical issues involved with removing a cat. If you want to discuss them, there is a Toyota Off Topic forum.

Please don't turn this into a debate. I need to find out why my cat failed prematurely so it doesn't happen again.

Hey BabyHuey:
Question: 50 to 100 degrees hotter or cooler goin' out the cat?
Thanks. <img src="/forums/images/graemlins/drunk.gif" alt="" />

I had a cat ruined from some gas I bought in Needles Ca. It had the words Leaded on the pump side from the days when that pump was a leaded station. My S-10 ran fine, till that trip. When you need gas in Needles, you get gas in Needles, there just isnt another on the next corner. (10 years ago) Destroyed the Cat, made a ton of back pressure for the manifold which in tern destroyed the manifold bolts, and overheated the clutch's plastic hydrauloc line, and I lost that. Too bad I was pulling a Uhaul to Texas.

POint is don't use leaded gas.

Right now, my starter is acting up. Each time I start, raw fuel gets dumped through the cold start injector and after turning the key a few times, it starts . That fuel doesn't all burn, so it pumps through the Cat. I am sure that it will destroy my cat if I dont fix it first. Luckily the cat isnt hot when that happens.

There are a couple of things that will destroy a cat. (back on topic)

Going out.Temp has to be hotter after gasses go through cat ,lets you know cat is good and hot and working.Fords are famous for cooling down the cat while waiting in line and flunking test.Its a good idea to run the snot out of anything right before testing.