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Thread: 05 trailblazer help!

  1. #1
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    05 trailblazer help!

    Posting 2 scan files and 2 tune files. Stock 4.2. Only changes were removing some torque management and removing pe delay and tps enable for pe. My 2 issues are the extreme kr and also appears to be some missed torque management on moderate acceleration. Looking for someone with more experience to take a look.
    Attached Files Attached Files

  2. #2
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    Anybody??!!??

  3. #3
    Tuning Addict 5FDP's Avatar
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    I think your kinda wigging out about something that isn't so serious. That amount of knock is pretty small and nothing compared to some stock vehicles running around. 87 octane is also far more prone to showing the knock compared to 89 octane or 91+.

    The 130-150 degree intake temps surely don't help that either.

    Those computers are kinda limited on tables to edit compared to others. If you think you have torque mngt kicking in you should be able to log something along the lines of torque mngt type as well as some of the spark correction tables that may be pulling timing away on you.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  4. #4
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    Quote Originally Posted by 5FDP View Post
    I think your kinda wigging out about something that isn't so serious. That amount of knock is pretty small and nothing compared to some stock vehicles running around. 87 octane is also far more prone to showing the knock compared to 89 octane or 91+.

    The 130-150 degree intake temps surely don't help that either.

    Those computers are kinda limited on tables to edit compared to others. If you think you have torque mngt kicking in you should be able to log something along the lines of torque mngt type as well as some of the spark correction tables that may be pulling timing away on you.
    Can you shed any light or understanding on the vcp spark table. Says spark modification based on variable cam but I'm not sure what the timing numbers refer to. Numbers look to large to be a spark modification.

  5. #5
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    To disable TM completely on these vehicles, you have to adjust both the Engine and Transmission side.
    Trans->Torque Management->General
    Engine->Torque Management->General

    For the VCP Spark, you have to take into account the corresponding modifier table "VCP Mult" to figure out what the timing is actually being told to do. For the actual VVT, you need to look at the Airflow->Variable Camshaft for the base, PE, and modifier tables. Think of it just like another spark table.

    If you're running 87, be prepared to pull a bunch of timing out, especially on today's gas. I pulled a bit of timing out of my 02 I6 and logged it, usually it only needed to be knocked down significantly during PE.
    ~Erik~
    2013 Sonic RS - manual, CGM, 6M, sunroof, mods in process
    2008 TrailBlazer 3SS AWD LS2, loaded, dropped, modded, SE22 Performance tuned. And then some...
    2002 TrailBlazer LT 4WD 4.2L I6, lifted, tires, exhaust, SE22 Performance tuned

  6. #6
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    Quote Originally Posted by ScarabEpic22 View Post
    To disable TM completely on these vehicles, you have to adjust both the Engine and Transmission side.
    Trans->Torque Management->General
    Engine->Torque Management->General

    For the VCP Spark, you have to take into account the corresponding modifier table "VCP Mult" to figure out what the timing is actually being told to do. For the actual VVT, you need to look at the Airflow->Variable Camshaft for the base, PE, and modifier tables. Think of it just like another spark table.

    If you're running 87, be prepared to pull a bunch of timing out, especially on today's gas. I pulled a bit of timing out of my 02 I6 and logged it, usually it only needed to be knocked down significantly during PE.
    thanks i appreciate it. The truck had 93 in it. On the vcp spark table what is it meaning exactly. base timing for that vct angle or is modified by that percent? Just trying to understand the table better to make an educated stab instead of just blind. I changed some of the trans tm. Did I miss any that you see?

  7. #7
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    These VCP Spark Base and Mult tables provide a modifier to final Base Spark (that's why they're listed under that section). The actual timing for the exhaust cam is listed under Airflow-> Variable Camshaft.

    Modifier isn't a percent, it's a whole/decimal number that's multiplied then added against the base table. It's been a bit since I've retuned my P10 as I'm happy with the tune, so I may be mixing this logic up a hair.

    To get final base spark, the PCM will calculate the corrections for IAT, ECT, VCP then see if it's in Cold start mode. It will then apply ALL of these together to the Base spark table in use. Let's assume sea level/high baro, 3200 rpms, 70kPa MAP, 111* F IAT, 208* F ECT using High Octane, non-PE tables for this scenario.

    Final Base Spark: 28* (rounded)
    IAT Base: -1*
    IAT Mult: 1
    ECT Base: -1*
    ECT Mult: 0.703
    Cold Launch: N/A (engine is not cold)

    We'll pick VCP up here in a sec.

    To calculate the spark modifiers the PCM will command:
    IAT modifier: -1* x 1 mult = -1*
    ECT modifier: -1* x 0.730 mult = -.7* (rounded)

    Now because this is a VVT engine, we have to add the VCP modifer in as well, BUT this is based off of the exhaust cam position. You have to calculate the actual commanded VCP using the same method for Spark as I posted above under Airflow->Variable Camshaft, THEN you can use that final cam timing to lookup the amount of VCP modifier to use.

    Fuel trim cell 10: 18*
    Both ECT and FTC mult tables are 1
    Final VCP timing: 18*

    VCP Base: 30* at 18* cam angle (PCM will interpolate between the 16* and 20* values)
    VCP Mult: 0.1 (PCM will interpolate between the 3000 and 3400 values)
    VCP modifer: 30* x 0.1 = 3* -> this is the actual amount of spark added at this particular operational condition to the final spark

    ECT + IAT modifiers: -1.7*
    VCP modifier: 3*

    Final commanded base spark: 28* + -1 + -0.7 + 3 = 29.3*


    Hope this helps out, a bit long winded but you have to know where the source values come from to determine what the changes actually do. I've gone through and simplified some of the multipliers and adders so the math is easier to do for me as a human (30 * 0.1 = 3 just seems unnecessary!).
    ~Erik~
    2013 Sonic RS - manual, CGM, 6M, sunroof, mods in process
    2008 TrailBlazer 3SS AWD LS2, loaded, dropped, modded, SE22 Performance tuned. And then some...
    2002 TrailBlazer LT 4WD 4.2L I6, lifted, tires, exhaust, SE22 Performance tuned