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Old 09-07-2017, 03:00 PM   #1
shultzee13
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Join Date: Jan 2012
Location: Tyler Texas
Posts: 182
Catalytic Converter Issues on 98 5.7L 2wd Suburban

The cat on bank 1 is rattling bad - the honeycomb is for sure broke apart but I am not getting a code P0420.
I am getting a code P0430 for bank 2. That cat is not rattling.

I am confused.

If the cat on bank 1 is rattling, wouldn't I get a code or am I not getting the code because the honeycomb is busted and it can breath?

Is there anything else that could be causing P0430 on bank 2 besides the Cat?

Both cats were replaced about 2 yrs ago. I could never beat the codes from coming back so I put in the defoulers. Someone said the defoulers can cause issues with running rich though.

I am just not sure what to do and I am tired of throwing money at it.
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Old 09-13-2017, 05:39 PM   #2
Cyphercrash
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Location: warner springs
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Smile Re: Catalytic Converter Issues on 98 5.7L 2wd Suburban

If BOTH cats were replaced 2 years ago, and , you know in your mind the honey comb in one is bad, unless you clunked it on a rock and did not tell us, I am going to assume you have a fuel issue. Running rich can definitely destroy a cat. I'm going to suggest you track down the rich run issue before throwing money at the cats again.
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Old 09-14-2017, 11:24 AM   #3
shultzee13
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Re: Catalytic Converter Issues on 98 5.7L 2wd Suburban

were do I start? I am getting 60PSI at the port. Turn key off and I have constant pressure for 30 min or more. So I know the regulator is good. The Fuel pump is 2 yrs old. The fuel filter I changed in March of this year. Do you have some suggestions on how I can check the spider? I am reading conflicting reports on google.
Could this be an internal engine issue?

I'm not a mechanic by any stretch, but I have replaced just about every electrical sensor on this truck since 2012 when I bought it.

Thanks for your help. I greatly appreciate it.
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Old 09-14-2017, 06:44 PM   #4
Cyphercrash
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Re: Catalytic Converter Issues on 98 5.7L 2wd Suburban

Quote:
Originally Posted by shultzee13 View Post
were do I start? I am getting 60PSI at the port. Turn key off and I have constant pressure for 30 min or more. So I know the regulator is good. The Fuel pump is 2 yrs old. The fuel filter I changed in March of this year. Do you have some suggestions on how I can check the spider? I am reading conflicting reports on google.
Could this be an internal engine issue?

I'm not a mechanic by any stretch, but I have replaced just about every electrical sensor on this truck since 2012 when I bought it.

Thanks for your help. I greatly appreciate it.
If one cat has broken honeycomb, back pressure to the second cat decreases, that cat blows code, there is no code for broken honeycomb, so the computer doesn't know what to do. Also many times the sensors you use for replacement are not AC Delco and can cause more issues than curing. Especially if you did not use a Delco ICM you will get screwed.
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Old 09-14-2017, 11:30 PM   #5
shultzee13
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Location: Tyler Texas
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Re: Catalytic Converter Issues on 98 5.7L 2wd Suburban

The one on bank one has now been replaced today. This was the one with the broken honeycomb. No more PO420. Bank 2 cat is good according to shop. Problem is I still have PO430.

I hate tearing apart plenum to get to spider if that not my problem. I guess the shop could be wrong but he said its good.

I am not sure how in the world I could tell the engine is dumping raw fuel or antifreeze into the Cat. A little water or something is coming from the exhaust put I was told it's just condensation. It does not smoke at all.

If I have a vacuum leak somewhere I got zero smoke popping out anywhere when I shot my fog machine through the brake booster hose and there is no hissing sound. I am down for whatever test is necessary. I just need someone to tell me what to do next and how. I will say my brand new ICM is "standard" brand not AC Delco. I also may have used teflon tape on the threads to my new ECT sensor. I learned today that is a no no, so tomorrow I will tape the tape off and reinstall. Surely the tape is not cause the truck the run rich and threw raw fuel into the cat. Not sure how I will prove it without replacing the Cat and the code not coming back.

I can post live data if needed. I have no other codes at all.

Thanks a million for your help so far.

Last edited by shultzee13; 09-14-2017 at 11:34 PM. Reason: Forgot one thing
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