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Thread: IAC Changed after TB ported???

  1. #1
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    Default IAC Changed after TB ported???

    At idle before the TB was ported the IACs were around 109 in closed loop, now after the TB was ported the IACs are maxed out at 310, When the car is first started up and is in closed loop for a min the IACs go down to 160s and then start raising up until it reaches 310 again.

    My car will not start good now when cold but a have to feather the throttle a little to keep it running for a few bit, and it gets better as it starts to warm up, and by the time it is in closed loop it is fine.

    Was my TB damaged when it was ported, or do I just need to lean it out in the Main VE table some more?
    Hers: 2001 Firehawk TransAm A4
    His: 2001 WS6 TransAm M6

  2. #2
    Lifetime Member jfpilla's Avatar
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    Default Re: IAC Changed after TB ported???

    Quote Originally Posted by Ladyredhawk
    At idle before the TB was ported the IACs were around 109 in closed loop, now after the TB was ported the IACs are maxed out at 310, When the car is first started up and is in closed loop for a min the IACs go down to 160s and then start raising up until it reaches 310 again.

    My car will not start good now when cold but a have to feather the throttle a little to keep it running for a few bit, and it gets better as it starts to warm up, and by the time it is in closed loop it is fine.

    Was my TB damaged when it was ported, or do I just need to lean it out in the Main VE table some more?
    I'm not real good with f-bodies, but from what I have been told, it seems like the ridge inside the TB has been worked. If it's gone it's a problem that you may not be able to completely resolve. It appears you are maxing the IAC values, now. Try turning the set screw some and get the IAC values to around 60 to 100.
    I've thought about my answer because the effect your getting actually seems to mean you're not getting enough air. It's possible the screw was adjusted or a different TB was returned to you.
    After you adjust the screw you need to do an idle reset. Do a search on LS1 Tech.
    At what rpm's and how much have you adjusted your VE's?
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  3. #3
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    Default

    Once the car is warm and the idle is stable, what are the IAC steps? Do you know if this is your original TB or if the adjustment screw has been moved?

  4. #4
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    Hey Guys, thanks soooo much for your help. They drilled out the whole for the IAC senor a little more and volla all is fixed. Tha senor wasn't getting enough air to read it right. My IACs are now 75 to 80 at idle. BTW he was told to drill out with a 1/4" drill but that was not enough for my car, not sure how big he went but a lot bigger than the 1/4. Thanks again guys, your great!
    Hers: 2001 Firehawk TransAm A4
    His: 2001 WS6 TransAm M6

  5. #5
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    Quote Originally Posted by Nick Williams
    Once the car is warm and the idle is stable, what are the IAC steps? Do you know if this is your original TB or if the adjustment screw has been moved?
    The IAC were at 310
    Hers: 2001 Firehawk TransAm A4
    His: 2001 WS6 TransAm M6

  6. #6
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    Nick, welcome to the forum. I'm not sure if other members know who you are, but your knowledge will be a great addition. Please check back often.
    \'04 Z16 Corvette, AFR 205 heads, Comp 228/232 114+4 LSA custom cam, HS Rockers, Kooks 1 7/8\' headers, 3\" X-pipe, stock Ti tail section. \'98 Corvette Pace Car, \'04 Chevy Avalanche Z71 4X4.

  7. #7
    Lifetime Member jfpilla's Avatar
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    Quote Originally Posted by Ladyredhawk
    Hey Guys, thanks soooo much for your help. They drilled out the hole for the IAC sensor a little more and viola all is fixed. The sensor wasn't getting enough air to read it right. My IACs are now 75 to 80 at idle. BTW he was told to drill out with a 1/4" drill but that was not enough for my car, not sure how big he went but a lot bigger than the 1/4. Thanks again guys, your great!
    Great, glad the hole worked. If you are ever in WS look me up.
    Joe
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  8. #8
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    Quote Originally Posted by jfpilla
    Quote Originally Posted by Ladyredhawk
    Hey Guys, thanks soooo much for your help. They drilled out the hole for the IAC sensor a little more and viola all is fixed. The sensor wasn't getting enough air to read it right. My IACs are now 75 to 80 at idle. BTW he was told to drill out with a 1/4" drill but that was not enough for my car, not sure how big he went but a lot bigger than the 1/4. Thanks again guys, your great!
    Great, glad the hole worked. If you are ever in WS look me up.
    Joe
    Ok we will! And if you make to the mountains let us know!
    Hers: 2001 Firehawk TransAm A4
    His: 2001 WS6 TransAm M6

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