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Thread: Spped density holden vehicles accounting for temp changes

  1. 08-10-2006 #1
    02sierraz71_5.3
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    Spped density holden vehicles accounting for temp changes

    How do the Holden vehicles that come from GM in Speed Density account for seasonal changes. I have to tweak my VE table for different seasons what has GM done to account for this?
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  2. 08-10-2006 #2
    Bowtie70SS
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    Are there seasons in Australia? LOL

    Dave
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  3. 08-10-2006 #3
    02sierraz71_5.3
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    Quote Originally Posted by Bowtie70SS
    Are there seasons in Australia? LOL

    Dave
    I think they have a hot and cold but the temps have to vary at least by 50 degrees through out the year.
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  4. 08-11-2006 #4
    Bowtie70SS
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    I was just being a smartass...I am jealous. I think we have a 100-120 temp swing in Ohio. There aer tables for IAT retard/advance though, but I don't know if it is disabled in SD mode.

    Dave
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  5. 08-11-2006 #5
    S2H
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    there is a temp bias table that accounts for both IAT and ET and helps to correct for varying temps and conditions...

    I have found that GM did not do too good of a job on this table and it is usually better suited to be a more even blend between IAT and ECT...(meaning closer to 1.0 in that table)

    If you dont have that table then its just hardcoded into the pcm OS...


    the table that you wold be looking for is on the airflow tab..same page as the VE and MAF tables...
    its called Cylinder Charge Temperature Bias
    -Scott -
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  6. 08-11-2006 #6
    02sierraz71_5.3
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    Quote Originally Posted by soundengineer
    there is a temp bias table that accounts for both IAT and ET and helps to correct for varying temps and conditions...

    I have found that GM did not do too good of a job on this table and it is usually better suited to be a more even blend between IAT and ECT...(meaning closer to 1.0 in that table)

    If you dont have that table then its just hardcoded into the pcm OS...


    the table that you wold be looking for is on the airflow tab..same page as the VE and MAF tables...
    its called Cylinder Charge Temperature Bias
    I read that entire thread it was a great read all 80 pages
    I set the bias to one a couple weeks ago and have notice a marked improvement in trims especially with my IAT's going over 130 in the heat.
    But, there is still a variation of at least 10% between temps going from 80 to 120 IAT They swing between a -5 +5 variation. Im sure there will be more when fall temps get here.
    What Im interested in is a year round speed density tune.
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  7. 08-11-2006 #7
    S2H
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    really more of the issue is probabaly that you are getting air temp of IAT where it sits and you my need to relocate it or get a better thermistor to do the job...when the IAT is more directly in the path of air and is as close as it can get to being insode the engine then your results will get much tighter...
    I noticed the different from in lid to in intake to be quite a large amount...
    I'm in OLSD all year round and I have no issues..fueling within 2% all the time now...
    -Scott -
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  8. 08-11-2006 #8
    brh26
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    Speed Density VE with IAT multipier

    This thread may help a little. I hope it is on the list for 2.1.14..
    http://www.hptuners.com/forum/showthread.php?t=5181
    cheers
    Brian
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