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Thread: idle adjustments and airflow

  1. #1
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    Default idle adjustments and airflow

    Newbie. Installed air box, intake, mild cam, heads, headers, exhaust.
    Remaining stock is the TB and MAF. CATS have been removed.
    I am using EFILive FlashScan V7.
    I have read thru a PCM tuning doc I found on LS1racer.com.
    I have got a bit of idle surging.
    Adjusted TB set screw. Unplugged TP sensor to reset it.

    IACDES_B (desired idle air control air flow) was significantly less than DYNAIR (dynamic air flow) So...
    Adjusted IAC effective area table to the right. Which definately helped idle.

    Idle surging is nearly all gone but other issues appear to have been created.

    LTFTs are positive approx. +4.
    Warm idle AFR is often going into 15s.
    WOT AFR is at 13.5

    Before TB set screw adjustment I had lots of idle surging. But.
    LTFTs are slightly negative or 0
    Warm idle AFR was in the 14s.
    WOT AFR is at 12.5

    Questions:
    1. PCM doc mentioned lowering base proportional. Where is that at in EFILive?

    2. PCM doc mentioned adjusting running airflow. Where is that at in EFILive?

    3. How do I fix the positive LTFTs. By adjusting the MAF table?

    4. PCM doc mentioned adjusting adaptive idle limits and/or air flow. Where is that at in EFILive?

    5. PCM doc mentioned adjusting idle airflow. Where is that at in EFILive?

    6. Is there any other table I need to tweek to fix the issues that have poped up?

  2. #2
    Lifetime Member TAQuickness's Avatar
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    Quote Originally Posted by heavyfoot
    Questions:
    1. PCM doc mentioned lowering base proportional. Where is that at in EFILive?
    I don't know

    Quote Originally Posted by heavyfoot
    2. PCM doc mentioned adjusting running airflow. Where is that at in EFILive?
    B4307

    Quote Originally Posted by heavyfoot
    3. How do I fix the positive LTFTs. By adjusting the MAF table?
    by returning your IACEA to stock, using the AutoVE tutorial to adjust your VE and or MAF, then adjusting your B4307

    Quote Originally Posted by heavyfoot
    4. PCM doc mentioned adjusting adaptive idle limits and/or air flow. Where is that at in EFILive?
    I don't know, but you shouldn't need to if you complete #3

    Quote Originally Posted by heavyfoot
    5. PCM doc mentioned adjusting idle airflow. Where is that at in EFILive?
    Return the set screw back to stock


    Quote Originally Posted by heavyfoot
    6. Is there any other table I need to tweek to fix the issues that have poped up?
    In some cases, adjustments to the throttle cracker/follower may be necessary.

    I wouldn't worry about desired vs actual airflows too much. But you should pay attention to the IAC step counts. Stock is in the 60-65 ish range at hot idle. You do not want to go lower than these values. I run mine in the 90-110 range.


  3. #3
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    oK...are you saying all idle problem can be resolved by recalibrating the VE tables? I guess I'm a bit confused. There is tons of documentation out there suggesting, drilling TB, adjusting TB screw, tweaking VE, tweaking spark, etc. or were you just giving me a starting point?

  4. #4
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    VE is crucial to EVERY SINGLE fueling calculation. without it, all other tweaks are kinda worthless. start with VE, once that settles, you can actually start looking elsewhere and see what needs to be adjusted.
    of course there's always my old writeup:
    http://redhardsupra.blogspot.com/200...le-tuning.html
    but this isn't exactly for a newbie. might point you in the right direction tho.

  5. #5
    Lifetime Member TAQuickness's Avatar
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    Quote Originally Posted by heavyfoot
    oK...are you saying all idle problem can be resolved by recalibrating the VE tables? I guess I'm a bit confused. There is tons of documentation out there suggesting, drilling TB, adjusting TB screw, tweaking VE, tweaking spark, etc. or were you just giving me a starting point?
    No. As RHS stated, VE is the back-bone to a proper tune. When the VE is dialed in (for the idle cells) you can then dial in the desired aire flow (b4307). VE and B4307 share an equal role in idle quality.


  6. #6
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    Ok...thx for the replies. Ill get started.

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