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No cat with TBI check engine light???

Discussion in 'The Garage' started by MTBLAZER89, Aug 31, 2004.

  1. MTBLAZER89

    MTBLAZER89 3/4 ton status Premium Member GMOTM Winner

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    If theoretically I was to remove my cat would this cause the check engine light to always be on?
     
  2. sled_dog

    sled_dog 1 ton status

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    o2 sensor is before the cat can't really see it causing a problem. I ran my 95 pickup with nothing more than Y pipe and a flowmaster 40 series with dual outlets. Never tripped the Check Engine Light. Heck running right out of the y pipe didn't /forums/images/graemlins/wink.gif.
     
  3. 1979jimmy350

    1979jimmy350 1/2 ton status

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    as long as you have OBD 1 you should have no problem
    if you have OBD 2 you need a o2 sensor sim from jegs or summit
     
  4. j20m715

    j20m715 1/2 ton status

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    I did this to a 98 truck & it did kick the light on.
    Without the backpresure it was confusing the computer.
    I ended up putting a hi-flo aftermarket cat on it.

    I know the tbi & vortec's are different but I think it will cause you problems.
     
  5. sled_dog

    sled_dog 1 ton status

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    your problem was simple, the 96+ chevys have at least 3 o2 sensors. 1 on each pipe of the y pipe, and one right AFTER the cat. This means if the cat is not there of course the system will know. It had nothing to do with backpressure.
     
  6. 1979jimmy350

    1979jimmy350 1/2 ton status

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    that is why you get a sim it plugs in where the o2 sensor was and tells the computer every thing is fine so you do not get any codes
     
  7. justinf

    justinf 1/2 ton status

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    Nope, like Sled-dog I ran my old 90 stepside with headers, Y-pipe, straight into a flowmaster, no cat, and never had a problem. /forums/images/graemlins/waytogo.gif
     
  8. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    [ QUOTE ]
    I did this to a 98 truck & it did kick the light on.
    Without the backpresure it was confusing the computer.
    I ended up putting a hi-flo aftermarket cat on it.

    I know the tbi & vortec's are different but I think it will cause you problems.

    [/ QUOTE ]

    Thats because OBDII has Pre and Post O2 sensors. On your '98 it has 4, and it would throw a code because both post O2 sensors will be switching, and there not supposed to be, not because of backpressure.

    No it shouldnt set a code on you TBI.
     
  9. Derf00

    Derf00 1/2 ton status

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    Gotta agree here. My '90 w/MPFI has headers, y-pipe into a Flowmaster. No problems.
     
  10. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    I have been running one of my TBI rides with no cat for over 10 yrs and have never set a code yet. These systems are archaic in today's technology (which is why I like them soooo much /forums/images/graemlins/thumb.gif).
     
  11. shaun

    shaun 1/2 ton status

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    Bryan,
    No it wont. On our trucks the o2 sensor is in the driver side manifold. So it will not cause any problems by removing the cat. And all the shopd here wont take your cat off but if you dont have one they wont make you put one on either. So take it off.
     
  12. jwduke

    jwduke 1/2 ton status

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    Brian, I removed the cat from my '87 & I have had no problems.
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    My 87 doesn't have a cat either.

    Hmm where the hell did it go? /forums/images/graemlins/rotfl.gif
     
  14. Jonny-K5

    Jonny-K5 1/2 ton status

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    i just swapped my high flow cat out for a straight pipe when i installed headers. i had the muffler shop fab it up to be removable with 3 bolt flanges. so i can replace the cat when it comes time to smog it.

    i have found two problems with this. first, i can smell excessive exhaust odors, like unburned fuel that the cat would have cleaned up. now i cant have my back window down, or even the front window at lights without getting a nasty smell.
    second problem is now when i drive on the freeway, and just cruise with very light throttle, the light comes on. i think its a code 32. what do you guys think? i think i'll replace the cat and see if it goes away. i dont like the smell anyway.
     
  15. sled_dog

    sled_dog 1 ton status

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    at this point I don't see a reason to not throw in a high flow cat. I'm going to on my Suburban, not my K5 just for ease but my next trail rig may very well get one.
     
  16. raelayotte

    raelayotte Registered Member

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    i have had my cat off for 5 years know and no check light yet /forums/images/graemlins/k5.gif <font color="yellow"> </font>
     

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