Are my Cats dead?

[mistaake]

Looking at this, I think they are... the vehicle wasn't fully warmed up but had been running for a while. It hasn't been driven a long distance for years so I think I have to take it on a long highway run to find out for sure but this looks pretty bad. Thanks in advance.

97 Burb 5.7 over 200K miles...

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[biggbiker]

Looking at this, I think they are... the vehicle wasn't fully warmed up but had been running for a while. It hasn't been driven a long distance for years so I think I have to take it on a long highway run to find out for sure but this looks pretty bad. Thanks in advance.

97 Burb 5.7 over 200K miles...

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[RichLo]

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[skylark]

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You read my mind!

 

[pro17]

There's no logic in the ECM to detect "if rear O2 voltage = front O2 voltage" obviously there's an issue with the cat, throw a code? sorry I dont know 1996+
And if it did throw a P-whatever code, in my area if there's a check engine light having to do with emissions, it has to get fixed before inspection.

 

[mistaake]

There's no logic in the ECM to detect "if rear O2 voltage = front O2 voltage" obviously there's an issue with the cat, throw a code? sorry I dont know 1996+
And if it did throw a P-whatever code, in my area if there's a check engine light having to do with emissions, it has to get fixed before inspection.

right, vehicle has not been operated long enough after changing battery for catalyst monitor to complete (currently it shows as incomplete)

 

[PeteyG708]

Is it throwing a code? If it is a P0420, then likely, yes. It looks to be oscillating fine, but like it has been said, it is not warmed up yet.

ETCG on Youtube has a great video explaining the P0420 and how the cats work. This is how I managed to figure it out on my truck.

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I’d say let it warm up and drive it around until the monitors complete, then you can get more definitive data (codes, data).

 

[Lanny]

Replacing a CAT isnt always the worst idea. They do plug over time especially if the engine hasn't been running right or has high miles. I need to replace mine this summer to hopefully bump my mileage up.

 

[Tachyon]

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.

 

[mistaake]

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.

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.