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Thread: Negative timing advance with out any knock retard?

  1. #1
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    Negative timing advance with out any knock retard?

    If any one could help me with this I would really appreciate it.

    Just swapped from a turbo 4.8 to 6.0 running speed density.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Try to log the channels that will show you where the timing going.

    Based on the IAT temps it's removing a few degrees of timing for sure, the rest is hard to say. Need to log some torque mngt channels to see where it's removing timing. Because this is a turbo setup you may want to raise your TM settings so it's not going to get in the way. Raise/remove the abuse settings too.

    Side note, your power enrichment and boost enrichment settings are very odd. Ideally you want the PE kpa to be around 80-90kpa, lower the enable torque to 80%. Remove the 7,000rpm delay. Have the PE commanded AFR less the boost enrichment AFR. Then tune the fueling to match the commanded AFR. Like right now you are asking for 12.45 but the wideband shows 10-10.5.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    Ill see if i cant log some torque mgmt.( it was disabled with the 4.8 and ran fine)
    I will try those and see what happens. Not sure why i had my boost enrich at 12.45 I will change that to around 12.8. Will also change PE.
    Thanks for the help.

  4. #4
    Tuning Addict 5FDP's Avatar
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    Why would you want to command an even leaner mixture under boost?

    The idea is to pick a fuel ratio and leave it, then tune the VE table to match that number. A safe number would be like 11.5 AFR under boost, so you pick 1.275 for boost enrichment (14.68/1.275 = 11.51afr). Then if your real AFR is say 10.3 at full throttle you would trim fuel out of the VE table to match your commanded value. This is where creating a wideband error against the commanded AFR comes in really handy. It will log the error percent and you can paste that value by half into you VE table, then smooth and repeat the process while making sure to keep the table smooth.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  5. #5
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    Log all timing and torque management modifiers. It will tell you what's going on and where to look.
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  6. #6
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    I totally agree with you I just figured I would be leavaing a lot on the table richer than 12.8.afr. So you think 12.8 afr would be risky? I only plan on running around 10psi.

    I deleted all torque management and manipulated the the main spark curve which seemed to help a lot. I logged about 4 runs tonight and have been trimming the ve with my wide band. When I initially floor it it looks like timing retards and then starts to creep back up.
    6.0 test 8.hpl

    I believe the only spark tables I left active were vs. IAT

    Again I really appreciate the help.

  7. #7
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    I deleted torque mgmt and TC.
    I'm not sure what i should log beside main spark. (which i cant get to read correct) having trouble setting up histogram in g/cyl. I believe the only spark modifier I have enabled is IAT. Can you suggest what spark table I log?
    I will add a log and tune if you feel like looking at it.
    Thank you for the help I really appreciate it.6.0 ve correction 8.hpt6.0 test 8.hpl

  8. #8
    Tuning Addict 5FDP's Avatar
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    Fueling for a NA engine and boost engine are way different.

    A good setup for a NA engine is roughly 12.3-12.8 for great power. On a boosted setup with regular pump gas you need to be down into the 11's, so say like 11.5.

    As I said in my previous post you need to make the commanded AFR match your actual AFR with the wideband. Look at your first logs, you are requesting 12.5 but the wideband shows 10's, so you have a major error there. Your VE table is way too rich to make the commanded match the actual. Running 12.5 or 12.8 on 10psi could cause piston damage.

    You have to remember than PE and BE settings are only to get set once and not touched again. So you set them to what AFR you want and leave them. Then you make all fueling changes to the VE to make that requested value match the actual value on the wideband. Like you ask for 11.5 but you see 10.3, you need to remove fuel from the VE so it gets closer to 11.5.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  9. #9
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    I understand that the PE and BE AFR wont be changed after its set. Not sure where we got crossed on that, it was only my ignorance on what it should be set at. I will set it to 11.5.
    I trimmed fuel out of the VE table 4-5 times this afternoon by percent-half and smoothed entire once each time, I just need to keep logging and trimming the VE.
    I just cant seem to figure out where the timing is going.

    Thank you for the quick response!

  10. #10
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    Quote Originally Posted by tjohnson View Post
    I just cant seem to figure out where the timing is going.
    Again, log all the timing and torque management modifiers... it will show you where the timing pull is coming from.
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