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  1. #1

    Default Engine dies when i let it idle.

    2003 5.3 silverado.I cut off both my catylitc converters today because they where both completely stopped up. I replaced each of them with a piece of stainless steel flexible exhaust tubing(2.5")(i didn't modify the O2 sensors at all). I had disconnected the neg battery cable a few days ago when i was changing the plugs and wires which reset my computer and started the process of relearning all the settings..it has always idled low and would sometimes die after the computer has been reset.. but after i replaced the cat's with straight pipe it seems like it is a lot worse. My question is: Did putting the straight pipes in place of the cat's cause anysort of fuel mixture or backflow problems.

  2. #2
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    Most likely not enough back pressure depending on what you have on for mufflers etc.. Also you will want to take a look at the Idle Air control valve. Since that part can build up carbon and not control the idle properly, or else the servo itself can quit.. Just something to look at as well.
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  3. #3

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    If you plan on not replacing the cats, than you should get a custom tune. Hand held programmers can't tune for no cats. I would get new cats, the truck will run better. You only lose about 3-4 hp on a stock truck with the cats. Alot of people say there truckruns better without the cats. Thats because the cats were plugged up and yes it runs better after removing the bad cats, but it will run ALOT BETTER with new cats. Magnaflow has good high flowing cats that are less than $90.00 each for your truck.

  4. #4

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    x2 for what silveradotrailblazer said (not to mention that removing the cats is illegal).

  5. #5

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    Quote Originally Posted by murdog94 View Post
    Most likely not enough back pressure depending on what you have on for mufflers etc.. Also you will want to take a look at the Idle Air control valve. Since that part can build up carbon and not control the idle properly, or else the servo itself can quit.. Just something to look at as well.
    Thanks. I will check the ICV

    ---------- Post added at 05:01 PM ---------- Previous post was at 04:54 PM ----------

    Quote Originally Posted by silveradotrailblazer View Post
    If you plan on not replacing the cats, than you should get a custom tune. Hand held programmers can't tune for no cats. I would get new cats, the truck will run better. You only lose about 3-4 hp on a stock truck with the cats. Alot of people say there truckruns better without the cats. Thats because the cats were plugged up and yes it runs better after removing the bad cats, but it will run ALOT BETTER with new cats. Magnaflow has good high flowing cats that are less than $90.00 each for your truck.
    I am going to replace the cats as soon as the money is avalible. Will i need to tune for the hi flow cats?

  6. #6

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    Quote Originally Posted by murdog94 View Post
    Most likely not enough back pressure depending on what you have on for mufflers etc.. Also you will want to take a look at the Idle Air control valve. Since that part can build up carbon and not control the idle properly, or else the servo itself can quit.. Just something to look at as well.
    Thanks. I cleaned the throtle body and put some lucas injector cleaner in last night and so far it hasn't died once while idleing.

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