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  1. #1

    Default Repeat check engine light for right bank cat threshold low.

    So I have done all four o2 sensors and the light will go away for roughly 150 miles then pop it comes back. I have replaced numerous normal wear and tear items. Plugs and wires, o2 sensors, IAT sensor and air filter and fuel filter. I have also cleaned the MAF with CRC cleaner.

    It has a minor stumble but still is getting about 17 mpg. Not happy with stumble, I think I have to check for a vacuum leak next but the Cat issue bugs me.


    I do not want the expense of replacing a cat converter in a vehicle we mainly only use for winter and for towing our race car and beach days.

    Thoughts? Oh Mine is 2002 Tahoe LT with autoride and E85 5.3L with 165K miles.

    Thanks Greg

  2. #2

    Default

    If you have replaced all that then it leaves the problem either being the CAT or an exhaust leak. BTW check amazon for the price of a CAT and as long as you don't live in Cali the cheapest one is only $60.(http://www.amazon.com/Walker-15053-C...1&s=automotive) That's alot less than the previous gen of truck CATs. Just use amazon's part search tool and you can find the part for cheap.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door

  3. #3

    Default

    Yeah, no leak in exhaust. Guessing it is the cat then, wondering why it's failing. That's cheap for a cat. Their size has drastically shrank over the years. In my early BMW's they are 3x the size of what the Tahoe has.

  4. #4

    Default

    Quote Originally Posted by M-technik-3 View Post
    Yeah, no leak in exhaust. Guessing it is the cat then, wondering why it's failing. That's cheap for a cat. Their size has drastically shrank over the years. In my early BMW's they are 3x the size of what the Tahoe has.
    CATs have become extremely more efficient as time has gone on. At this point CATs barely cause any restriction in the exhaust like the olds ones did. They also have gotten cheaper because of competition between exhaust manufactures.

    Why is it failing, heres a few possibilities:
    1. Coolant or oil leak in to a cylinder that burns the fluid which can clog or damage a CAT
    2. Excessive vibration, heat and time can damage the catalyst or break it down causing it not to work.
    3. It may just be used up. The catalyst does not last for ever over time it will be used up and no longer be able to absorb/convert as many elements as when new. The ECM is smart enough to know when the CAT is well beyond the specs.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door

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