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Thread: Truck uses Throttle Follower P/N Tables when In Gear

  1. #11
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    Quote Originally Posted by ferocity02 View Post
    Because it works well enough for me without the clutch switch hooked to the PCM, no need to add complexity to the tune either.

    The question here is if a manual tune does use P/N tables when the clutch is depressed or when it's in neutral, why are the idle P/N tables zeroed out in stock manual tunes? And why does it use the P/N throttle follower tables but no other P/N tables? My truck is clearly using the In Gear tables for some things, and the P/N tables for others. At this time, and without further understanding, I don't see how adding the clutch switch will help this.

    I also don't understand how the PCM knows when the trans is in neutral, other than the clutch being depressed, or if VSS is 0 and RPM is > 0.
    What I was trying to say is you are adding complexity to the tune by not wiring it up like GM did. You are spending loads of time troubleshooting issues that simply wouldnt exist if you connected the CPP to the PCM. It is great that it is working without it hooked in, but I think you're running in circles trying to figure out a way around a simple issue that is easily remedied. To me, the easiest way to find a solution would be to run the wires to the PCM from the CPP and any other sensor that a factory manual truck would have so it is exactly like GM would have wired it. Then start with all of GM's stock settings for a 4.8L manual (only one I know that came with a manual) and start tweaking from there.

    I do not know exactly how the PCM determines gear with a manual trans, I think Joe posted about it a week or two ago. I believe it is a combo of RPM and VSS, but dont quote me on that.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  2. #12
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    Quote Originally Posted by ScarabEpic22 View Post
    What I was trying to say is you are adding complexity to the tune by not wiring it up like GM did. You are spending loads of time troubleshooting issues that simply wouldnt exist if you connected the CPP to the PCM. It is great that it is working without it hooked in, but I think you're running in circles trying to figure out a way around a simple issue that is easily remedied. To me, the easiest way to find a solution would be to run the wires to the PCM from the CPP and any other sensor that a factory manual truck would have so it is exactly like GM would have wired it. Then start with all of GM's stock settings for a 4.8L manual (only one I know that came with a manual) and start tweaking from there.

    I do not know exactly how the PCM determines gear with a manual trans, I think Joe posted about it a week or two ago. I believe it is a combo of RPM and VSS, but dont quote me on that.
    By complexity I mean having to adjust both P/N and In Gear tables rather than just one or the other. I have yet to find an LS1B tune for a manual 4.8L. Do you have one?
    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

  3. #13
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    I havent, one of my buddies has one but he lives 5 hours away from me and I didnt have my V2 when I saw him last.

    If someone has a VIN for a manual 4.8L, I can bench flash my LS1B PCM with it the next time I use Tis2Web then read it out for everyone.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  4. #14
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    I take back what I said earlier... it is hit and miss whether or not the truck is actually using the throttle cracker table. I kept adding air but it seemed like nothing was happening, so I made the entire table 12 g/s to see if it really was working, and it was, but it seemed to only add the air when I am first starting off from a stop, then it would decay out as I continued to drive for 5-10 seconds. Very strange... I even made the P/N and In Gear cracker tables the same and it did the same thing.

    How can I figure out if throttle cracker/follower are active? I've been logging GM.IAC "Idle Air Control Position" to see the steps and then GM.IACDES_B "Desired IAC Air Flow". Can someone explain exactly what IACDES_B is? I was thinking it's the sum of idle, cracker, and follower airflow. But at idle it displays about 0.4 g/s less than my desired idle airflow.

    I logged GM.TSTATE00 "Transmission State 00" and a bunch of other transmission stuff, and it said that my clutch is depressed all the time, except when I turn the engine off then it says released. None of the other trans PIDs were informative, but it does recognize that it's an "M6".
    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

  5. #15
    Lifetime Member darcy's Avatar
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    Quote Originally Posted by ferocity02 View Post
    How can I figure out if throttle cracker/follower are active?
    Try logging GM.IAC_TC_DMA and GM.IAC_TF_DMA for Cracker and Follower.

  6. #16
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    Quote Originally Posted by darcy View Post
    Try logging GM.IAC_TC_DMA and GM.IAC_TF_DMA for Cracker and Follower.
    They aren't available for my PCM :(
    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

  7. #17
    Joe (Moderator) joecar's Avatar
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    You might be able to change OS to one that supports the _DMA pids.

  8. #18
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    Quote Originally Posted by ScarabEpic22 View Post
    I havent, one of my buddies has one but he lives 5 hours away from me and I didnt have my V2 when I saw him last.

    If someone has a VIN for a manual 4.8L, I can bench flash my LS1B PCM with it the next time I use Tis2Web then read it out for everyone.
    Does your buddy have a dbc or dbw 4.8 manual tune? I assume the op is looking for a dbc 4.8 manual tune?
    1997 S10, 06 trailblazer SS LS2 swap, 4L70E trans, 76mm turbo. Factory ZQ8 suspension. 3.08, G80 w/a zexel. With a 0411 swap.

  9. #19
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    OP, minitryker posted a 4.8 manual tun exactly 4 weeks ago in this forum. Not very hard to find if you know where to look. Also contrary to forum belief that a 4.8 was not the only truck to come with a manual. There were quite a few 6.0 lq4 with a manual trans over many year models.
    1997 S10, 06 trailblazer SS LS2 swap, 4L70E trans, 76mm turbo. Factory ZQ8 suspension. 3.08, G80 w/a zexel. With a 0411 swap.

  10. #20
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    Something is definitely funky... A log I made shows throttle cracker airflow being added suddenly at random times and then quickly decayed out. Sometimes it is added in odd double-spikes which start right when I hit 18 mph, and it adds 6 g/s which is correct (see frame 1024). Then then sometimes it will add it when I hit 3 mph which is the correct TC activate speed, here too it also adds the correct amount (see frame 690).

    Perhaps it's calculating something in the background so when it hits 18 mph it suddenly thinks it's in gear. Clutch switch or not, this isn't right.

    I might go back to the auto tune since I didn't have any issues with that.
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    2001 Silverado 5.3L ECSB 2WD T56:
    T76 turbo, Meth injection, 72# injectors, 799 heads, 212/212 114LSA cam, Built 4L80E, 3.42's
    EFILive V1 Commercial, COS5 2-bar SOLSD, AEM wideband

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