Are my Cats dead?

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pro17

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If you do need to replace them, Magnaflow makes high flow replacements that seem to work well.
Meanwhile, I'd grab some of that fuel additive designed to help you pass emissions, throw it in the tank, and take the old girl on a nice long highway run. See if that helps burn off the particulates. Modern cats (ie not the old pellet type) like in your truck really don't clog up very easily and are designed to burn off buildup if it's not too bad. Most cats that fail are due to physical damage or really out of band engine conditions (eg running really rich for a really long time).
Also, make that fillup with ethanol free fuel so that you're not running rich.

Ethanol free gas fuel makes your engine run richer btw
 

Tachyon

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Thanks, I did put a bottle of CRC guaranteed to pass in there, once I get it back together I'll take it on a nice highway trip. There is no ethanol-free gas around here in California...

It was running with a stuck open injector on cyl #8 for who knows how long before I bought it so I don't have high hopes for the cats lol. I did put a new injection spider and it runs good now so at least the cat isn't plugged, it's just unhappy. Hopefully my highway run helps, I'll report back probable sometime next week when I have time to drive it.

When my old fuel spider failed, it also failed with an open injector and it left a mess in the engine and no doubt the cats. I was worried I'd have to replace them. But, after running the Lucas stuff every other tank for 3 tanks it really cleared up and I stopped getting (mostly) codes from the after CAT O2 sensors.
I'm going to put another can in today actually and I think I'll start doing that every other month or so for maintenance purposes.
That said, if you're running the original factory CATs you may be right. They may be beyond help. But it worth a try for the cost of a can of product.
If you do have to replace, not only am I happy with the Magnaflow cats, but honestly they were the only "performance" CAT's I could find for that vehicle. Everything else is the stock ones. Their whole manifold back + CATs kit is pretty decent and surprisingly reasonably priced.
 

Tachyon

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Ethanol free gas fuel makes your engine run richer btw

Yes, but if you have a sticking injector that is already forcing your engine to run rich, then running ethanol free fuel leans it out a bit compared to ethanol "enriched" fuel in the same conditions.
 

pro17

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Yes, but if you have a sticking injector that is already forcing your engine to run rich, then running ethanol free fuel leans it out a bit compared to ethanol "enriched" fuel in the same conditions.

That's not true and I have proof in tunerpro logs where I also had a sticky injector and before E0 BLM was at about 215 at idle, which could be consistently be duplicated, then i drained the tank and added 3 gallons of E0 and began to bottom out at 208 and even burned a chip to lower the threshold and ended up settling at like 204. Less O2 in the exhaust so the computer removes fuel
 
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