Catalytic converter life?

I'm curious who has replaced their cats, how many miles you got, and how you knew your cats were plugged. Do they generally throw a code?

My gas mileage has dropped from 16-18 to 12-14, and it seems the power under load has dropped. Aside from that the truck seems fine. No codes. Plugs, AF, MAF, TB all OK, so I'm suspicious that the cat may be getting plugged. 106,000 on the clock, mostly highway.

I have not checked the air intake for obstructions, so I will do that. Looking for whatever you guys might know that will help before I get really dirty.

Thanks!

 

If you suspect your cat(s) are plugged, maybe you could try this: http://www.aa1car.com/library/exhaust_backpressure.htm

 

the best and true way to tell if a cat is clogged is they(muffler shop) drill a tiny hole infront of the cat and insert a metal thing that reads back pressure.
then if cat is fine they weld it up as it as a hole smaller then a tip of a pen.

most cats last about 120k ,there are way to many variables to tell exactly ho long they can last.i have seen some but few that last upto 300k

to be honest on thing almost every one skips is the o2 sensors as they go bad around 80k to 100k ,they get clogged and the pluses start getting erratic.throws of you A/F when bouncing around to much.(the electric signal) (can last longer)

 

I'd agree.

On Subarus, the cats were very very robust and almost never failed or plugged unless something was seriously wrong with the engine. People would prematurely replace them (and the OEM part was expensive) when it was usually just an O2 sensor. So, definitely check that first.

 

Sub'd

 

Thanks for the input guys. I did think about the O2 sensors but I figured a faulty sensor would throw a code. Has anyone seen a bad sensor NOT throw a code? Whether the cats are bad or not, it is probably not a bad idea to replace the sensors. I could try that first, then go deeper if needed.

 

Just replaced the cats on my 2.7 yesterday. Since I am in CA the part alone was almost $1600. :/. . I had just hit 115k miles. I replaced o2 sensor and the air fuel ratio sensor also. I was unsure if it was clogged or getting clogged until a couple days ago the exhaust was super loud and I had no power at all.

 

Oh and I had no codes being thrown.

 

I started to get an intermittent P0420 code at about 85K. After checking for leaks and finding none I bought a dorman kit from rockauto for $250.
Comes with the cat, gaskets, and most hardware. I had to buy the manifold bolts from my local hardware store for less than $5. I would recommend using a 6 point socket when removing the manifold bolts since they round very easily with a 12 point. 10K miles later all is well.
I took the old OEM cat to a local guy who buys scrap and he looked up the numbers on the cat and they fall into a category called
"low grade foreign". I got $30 for it!

 

That's why I love TW; specific advice from knowledgeable members.

 

Are you in CA? My smog guy said a generic cat would not pass the new Ca visual inspection

 

I'm in Pa and have no emission testing in my county. I changed it just to make the engine light go off.
Your smog guy said a generic cat won't pass a "visual" inspection?
I thought a visual inspection was just checking to see if it's there?
From what I have read, Toyota went cheap with our cats. Mine was just out of warranty. and the scrap guy said it was not worth as much since the metals inside were less than other cats. I got $70 for a cat I took off my Civic. $30 for the Tacoma cat.
I don't know, your state start all kinds of stupid laws that effect the rest of us like those damn spill proof gas cans that spills gas everywhere.

 

Yeah CA laws suck. CA now requires CA cats and they match the code printed on the cats to the engine. Its absolutely ridiculous!

 

Here in part of an article about decreasing gas mileage:
http://artsautomotive.com/publications/8-automotive/166-the-mileage-story/





An explanation of the O2 sensor and feedback system
Internal combustion engines run well with rich mixtures. It’s not uncommon to find a car that runs just fine, but sucks a lot of gas. In the days before computer control, cars were designed to run a little too rich all the time. Too little gas (a lean mixture) will cause a car to run poorly, whereas the mixture would have to be grossly rich before a car will start to run poorly. Without computer control, there was no way to accurately trim the mixture to 14.7 to 1, so the designers erred on the rich side. The O2 sensor was one of the first sensors monitored by computer control systems. The O2 sensor sits in the exhaust stream and sends a signal to the computer: over .6 volt if too much gas is being added, under .6 volt if there is not enough gas being added. The computer would use this signal to control a solenoid in the carburetor that would reduce or increase the mixture as necessary. Cars have come a long way since then, and the last carburetors were fazed out by the late 80s. However, the O2 sensor, and it’s newer incarnation the AF sensor, are still in use today, and still play an important roll in increasing fuel economy and reducing emissions. When O2 sensors fail, they can’t read rich and are slow to respond to changes. This translates into a rich mixture most of the time, which will cause your car to use more gas. Some of the newer computers will notice when an O2 sensor starts to wear out, but most will just keep on adding too much gas. When a car is getting poor mileage, the O2 sensor should be checked.

 

That's nuts, they actually crawl under there and look?

 

Yep. Bullshit isn't it?!

 

You didn't have to replace cat. Just take it out and clean it. I did mine. Dealer asked me 1.7k for it but no thanks. It cost me $18 for new gasket and 6oz of Dawn dis washing soap

 

Did you hose it out with a garden hose? In for more info on this....

 

If the cat is truly clogged like mine was with the internal metal rolling around inside and plugging the exit I don't think soap would work. I sure wish though!

 

I'm interested to hear in more detail how this soap worked out. As there was a guy on a Tundra forum that built a setup out of a spare dishwasher, that ran acid or something like that through it at high temp.

Apparently the guy is still driving around after the cleaning with no codes. Would be great to hear you could simply clean it out with soap.