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Question after LT's

This is a discussion on Question after LT's within the Computer & Tuning forums, part of the LSx Technical Help Section category; In reguards to emmissions testing. Is it safe to say that if no check engine light comes on I should ...

  1. #1

    Question after LT's

    In reguards to emmissions testing. Is it safe to say that if no check engine light comes on I should be able to pass the plug in test? Or will the car need to be tuned?

  2. #2
    Junior Member Shakingchevy's Avatar
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    i think that you should pass them... but im not sure

  3. #3
    Quote Originally Posted by Shakingchevy View Post
    i think that you should pass them... but im not sure
    me2 haha

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    Stockitie Stock Stock 95camaroZNC's Avatar
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    Were the lights tuned out of the car? If so then yes. Youll pass.

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    Member ls1wallen's Avatar
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    Give it a couple days it will pop on. It takes a few runs

  6. #6
    Auto Painter RyanJM's Avatar
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    After reoving the egr with the LS6 intake and installing the QTP race headers. They deleted the rear 02's and EGR with the tune and I pass the OBD2 test with no problems. Justt gotta go to a station that doesn't look under your car. I know a few that look pass everything else like LT's and tint as long as it passes the computer and you have to remember to always tip you inspector.
    1998 Trans Am 85k miles.
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  7. #7
    So I can expect the check engine light to come on??

  8. #8
    Moderator Cutlass's Avatar
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    It depends. Did you keep the cats, EGR (not sure what year your car is), and AIR. If so, then you might get lucky and everything will work ok. It not then yes, your SES light will come on and you'll fail emissions untill you get a proper tune

  9. #9
    You've Seen The Butcher GoldenFlame's Avatar
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    Quote Originally Posted by ls1wallen View Post
    Give it a couple days it will pop on. It takes a few runs
    My SES came on 45 seconds after my first fire lol

    !cats
    !EGR
    !AIR

  10. #10
    Yes im keeping the cats and egr/air

  11. #11
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
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    I got rid of all that junk on the 02 and had all of it tuned out.

    Passed the plug in test and gas cap test with flying colors earlier this year.
    67 Camaro: K-K + 797-z (look it up), 454/Th400/4.10 12-bolt = 6mpg, PS/PDB/PW tilt, tach, gauges...

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    2002 Z28: NBM/Tan, MTI smooth lid, smooth bellows, !AIR, !cats, 1-3/4" QTP SS LT's, 2-1/2" TD's with X-pipe, MagnaFlows dumped at axle, custom welded SFC's, MidWest Chassis body mount adjustable T/A, 3400 stall, 3.23 gears (was 2.73). Tuned: 343rwhp/357rwt (before TD's). Best: 12.559 @ 108+, 1.73 60' @ 3500' DA w/MT ET Street DR's.

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  12. #12
    Well LTs/Texas catted Y pipe are in. No engine lights came on and the car doesnt smell at all. Do you think I should pass the plug in without a tune?

  13. #13
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
    Sadly now demodded :(

    Quote Originally Posted by Mike0202 View Post
    Well LTs/Texas catted Y pipe are in. No engine lights came on and the car doesnt smell at all. Do you think I should pass the plug in without a tune?
    I'd have it scanned 1st just to be sure there are no stored codes.

  14. #14
    Senior Member rajiv1998's Avatar
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    Quote Originally Posted by 67CamaroRSSS View Post
    I'd have it scanned 1st just to be sure there are no stored codes.
    I would be afraid if I installed LT's and no lights came on.
    "Life is to short to drive a slow car"

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  15. #15
    Quote Originally Posted by rajiv1998 View Post
    I would be afraid if I installed LT's and no lights came on.
    Why would I want engine lights on?

  16. #16
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
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    Quote Originally Posted by rajiv1998 View Post
    I would be afraid if I installed LT's and no lights came on.
    When I had my LT's installed the dude also deleted the codes for the rear O2's. This, along with the AIR requirements, were the only items that needed to be deleted in order for the PCM to run clean, i.e., with no codes. This allowed me to pass the "Smog" requirements I have to pass every 2 years.

  17. #17
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
    Sadly now demodded :(

    Quote Originally Posted by Mike0202 View Post
    Why would I want engine lights on?
    Not altering the PCM values for the AIR and rear O2's after installing LT's w/o the AIR setup and without the cats will throw a code (SES light on the dash) that the PCM will store. You need to have these altered and deleted from the PCM to run clean at the Smog Check station.

  18. #18
    Quote Originally Posted by 67CamaroRSSS View Post
    Not altering the PCM values for the AIR and rear O2's after installing LT's w/o the AIR setup and without the cats will throw a code (SES light on the dash) that the PCM will store. You need to have these altered and deleted from the PCM to run clean at the Smog Check station.
    I was told it would throw a code without cats thats why I had them put high flow cats on. All I have to pass is a plug in test.

  19. #19
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
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    Quote Originally Posted by Mike0202 View Post
    I was told it would throw a code without cats thats why I had them put high flow cats on. All I have to pass is a plug in test.
    I would have deleted the cats also. AAMOF, that is exactly what I did as I only have to pass the plug in and gas cap vacuum test also. Technically your not in compliance anyway as the catalytic converter position has been altered from stock.

    Your PCM can be set up to reflect the lack of a Cat without throwing a code. The rear O2 sensors only measure cat converter efficency anyway, they are not required to run the car.

    In for a penny, in for a pound...

  20. #20
    Quote Originally Posted by 67CamaroRSSS View Post
    I would have deleted the cats also. AAMOF, that is exactly what I did as I only have to pass the plug in and gas cap vacuum test also. Technically your not in compliance anyway as the catalytic converter position has been altered from stock.

    Your PCM can be set up to reflect the lack of a Cat without throwing a code. The rear O2 sensors only measure cat converter efficency anyway, they are not required to run the car.

    In for a penny, in for a pound...
    True. I was thinking about ditching the cats but I dont like any rasp what so ever. Sounds pretty mean with high flows.

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