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Thread: E38 ECM speed density won't start until MAF fails.

  1. #1

    E38 ECM speed density won't start until MAF fails.

    08 Silverado running a speed density tune. After a new tune is flashed it won't start at times. Once the MAF fails it will start fine until you flash it again. MAF fail set to 0hz, P0101,p0102,P0103 all set to 0 first error. MAF table is zero out.
    It getting really frustrating trying to get it started. What's going on that I'm missing?

  2. #2
    Senior Tuner mowton's Avatar
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    Put 6 g/s (or about what the RAF would be set to at idle) in the MAF 0 HZ cell.

    should help you ride through the fail setup.

    Post your tune please.

    Ed M
    Last edited by mowton; 09-15-2012 at 03:47 PM.
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

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  3. #3
    Senior Tuner IDRIVEAG8GT's Avatar
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    Whatever you do make sure you don't kill it till 30 seconds after the fail process!

    Don't worry OP my G8 is being very fussy about it too.
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

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  4. #4
    Senior Tuner DSteck's Avatar
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    Cycle the key if you aren't already.

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  5. #5
    Tried cycling the key and repeated reflashing. It's pissing me off.

  6. #6
    HP Tuners Support
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    Bill@HPTuners's Avatar
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    Start by posting your current tune.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  7. #7
    Here it is.

  8. #8
    Senior Tuner IDRIVEAG8GT's Avatar
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    Does your truck have an issue with the TPS going down at idle when the MAF fails?
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap

  9. #9
    Potential Tuner Steve@HPE's Avatar
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    Quote Originally Posted by scooter k View Post
    08 Silverado running a speed density tune. After a new tune is flashed it won't start at times. Once the MAF fails it will start fine until you flash it again. MAF fail set to 0hz, P0101,p0102,P0103 all set to 0 first error. MAF table is zero out.
    It getting really frustrating trying to get it started. What's going on that I'm missing?
    I had similar behavior and resolved it by increasing the values in the VE tables in the idle area and adding airflow in the idle range to the MAF Airflow vs HZ table.

    Also, the VE correction factor table creates a bias of MAF vs VE airflow, you may want to make sure that's completely biased to VE. Although, I suspect that table is ignored once the MAF fails, but it may play a role in the mean time.

    BTW, there are areas of negative timing in your "Cranking Spark" table.

  10. #10
    Senior Tuner IDRIVEAG8GT's Avatar
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    Quote Originally Posted by Steve@HPE View Post
    I had similar behavior and resolved it by increasing the values in the VE tables in the idle area and adding airflow in the idle range to the MAF Airflow vs HZ table.

    Also, the VE correction factor table creates a bias of MAF vs VE airflow, you may want to make sure that's completely biased to VE. Although, I suspect that table is ignored once the MAF fails, but it may play a role in the mean time.

    BTW, there are areas of negative timing in your "Cranking Spark" table.
    You part of Hennesey?
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap

  11. #11
    HP Tuners Support
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    considering you have the maf table 0'd out its pretty normal that the pcm wouldn't run UNTIL you set the maf to fail.

    /thread.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  12. #12
    Senior Tuner DSteck's Avatar
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    I don't understand why people zero the MAF table for SD.

    DSX Tuning - Authorized HP Tuners Dealer
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  13. #13
    HP Tuners Support
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    I believe the custom operating system application process automatically 0's out the maf & ve tables(because it extends the maf table and creates a ve table from scratch), we've found that in most cases the ve table must have at least some sort of baseline even if running SD only(not sure why this is but it is what it is I suppose).
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  14. #14
    So I need to put something in the MAF table then even though there isn't a MAF at all? Anything else?

  15. #15
    Senior Tuner DSteck's Avatar
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    Quote Originally Posted by Bill@HPTuners View Post
    I believe the custom operating system application process automatically 0's out the maf & ve tables(because it extends the maf table and creates a ve table from scratch), we've found that in most cases the ve table must have at least some sort of baseline even if running SD only(not sure why this is but it is what it is I suppose).
    The only MAF table that gets zeroed out is the MAF High in applications that have two MAF tables.

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  16. #16
    Potential Tuner Steve@HPE's Avatar
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    Quote Originally Posted by IDRIVEAG8GT View Post
    You part of Hennesey?
    No....Hines Performance Engineering. I have family members that race/build motorcycles you may have heard about, but I do cars.

  17. #17
    Senior Tuner mowton's Avatar
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    Is my 2nd post invisible
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

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  18. #18
    Senior Tuner IDRIVEAG8GT's Avatar
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    Quote Originally Posted by mowton View Post
    Is my 2nd post invisible
    WE ARE ALL BLIND!
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap

  19. #19
    Senior Tuner IDRIVEAG8GT's Avatar
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    Quote Originally Posted by Steve@HPE View Post
    No....Hines Performance Engineering. I have family members that race/build motorcycles you may have heard about, but I do cars.
    Sweet, I'm glad you're not. I was about to bash you about Hennesey screwed up DynoJet.
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap

  20. #20
    Senior Tuner mowton's Avatar
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    Quote Originally Posted by IDRIVEAG8GT View Post
    WE ARE ALL BLIND!
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
    HP Tuners Dealer- VCM Suite (free 2hr training session with purchase), credits and new Version 2.0 turtorial available
    http://www.ermperformancetuning.com
    http://www.facebook.com/ERMPerformanceTuning

    [email protected]