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Thread: Transient Fuel: Tips, Tricks, and Info. A how-to guide

  1. #61
    Advanced Tuner lt1z350's Avatar
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    need a reminder to read later good stuff here
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

    2013 cadillac ats 2.0t Big turbo-gone
    2007 tahoe 5.3 lsa blower on 14 lbs boost 6l80e swap 2009 os
    2017 zl1 a10 big gulp/2 inch headers/ 9.55 lower/ e85/bigger hx /103mm tb / Synergy trunk tank and underhood kit/methanol injection with torqbyte controller and prometh pump / Jokerz performance R&D ported stock blower/ lme cnc heads /GP tuning custom cam. So far 9.30@150

  2. #62
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    I have been having massive lean tip in issues with my speed density open loop ls1 383 stroker. I have a large cam with lots of overlap, AFR 230cc heads and a FAST 102 manifold and throttle body. Below 3000rpm anywhere from 55kpa - 100kpa I would get huge lean spikes by rolling into the throttle. This was with a near perfect tuned steady state VE table. For reference I Multiplied the 100Kpa row of the Impact Factor table by 2 and interpolated back to the 60Kpa row at all coolant temps. My Lean tip in is more or less gone and throttle response is up. Some more fine tuning would nail it down some more but great results with little effort so far. I definitely recommend playing with this table if after Steady State VE tuning you still have transient problems.

  3. #63
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    Quote Originally Posted by toolbag92 View Post
    I have been having massive lean tip in issues with my speed density open loop ls1 383 stroker. I have a large cam with lots of overlap, AFR 230cc heads and a FAST 102 manifold and throttle body. Below 3000rpm anywhere from 55kpa - 100kpa I would get huge lean spikes by rolling into the throttle. This was with a near perfect tuned steady state VE table. For reference I Multiplied the 100Kpa row of the Impact Factor table by 2 and interpolated back to the 60Kpa row at all coolant temps. My Lean tip in is more or less gone and throttle response is up. Some more fine tuning would nail it down some more but great results with little effort so far. I definitely recommend playing with this table if after Steady State VE tuning you still have transient problems.
    Would this lean tip cause your car to stumble as it happened ?

  4. #64
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    Does this look like a transient issue. This is a 24x lt1 so the transient tables have to be different. But I get a strong lean in when I get into the throttle below 3k. It's got heads and 234/244 cam. It also seems to only happen on warm up. I believe it still happens when warmed up just not as noticeable.
    Also this is a speed density open loop tune. I don't think it was as noticeable when running in closed loop bc the oxygen sensors seemed to correct it
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    Last edited by anniversaryss; 11-01-2018 at 11:36 PM.

  5. #65
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    great information gentlemen thank you

  6. #66
    Tuner miami993c297's Avatar
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    Quote Originally Posted by toolbag92 View Post
    I have been having massive lean tip in issues with my speed density open loop ls1 383 stroker. I have a large cam with lots of overlap, AFR 230cc heads and a FAST 102 manifold and throttle body. Below 3000rpm anywhere from 55kpa - 100kpa I would get huge lean spikes by rolling into the throttle. This was with a near perfect tuned steady state VE table. For reference I Multiplied the 100Kpa row of the Impact Factor table by 2 and interpolated back to the 60Kpa row at all coolant temps. My Lean tip in is more or less gone and throttle response is up. Some more fine tuning would nail it down some more but great results with little effort so far. I definitely recommend playing with this table if after Steady State VE tuning you still have transient problems.
    Any downside you can notice?


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  7. #67
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    Any updates on this topic?
    Last edited by marksrig; 02-23-2020 at 07:01 AM. Reason: Any

  8. #68
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    Whoa. Been tackling a new issue with transient fueling after swapping intakes on the same motor this write up was, well, written up for.

    Completely forgot I wrote this, and was googling and found it haha!

  9. #69
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    Quote Originally Posted by SVT_Z06 View Post
    Great info guys!

    "Log IBPW at idle. For example, lets say your idle IBPW is 3.2ms
    Divide this value by 31.124308 this will give you 0.1028135. Place 0.10 in min fuel in mg."

    Does this still hold true? I'm seeing 1.5 IBPW, so does that mean I need to change my min fuel in mg to 0.048?
    This was never answered, is this accurate?

    My min IBPW is 1.5ms with 36lb GTP injectors and 0.048 min fuel in mg is higher than stock setting of 0.041.
    Or would 0.014 setting be a correct value?
    Last edited by cino; 08-29-2021 at 12:01 PM.

  10. #70
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    I'm new to tuning, but have dove into the deep end while knowing only how to dogpaddle. I've read through this thread and copied the Maths into my Maths folder. Could someone add some detail on how to set up the graph for this to properly work?
    On my '52 Cadillac with 6.0/4L70 TSP Stage II Low lift, LS6 intake and injectors I've got my MAF and VE dialed in, but occasionally get hit up to tune other GenIII swapped vehicles. This method would save some time.

    20210309_212403.jpg

  11. #71
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    I know this is an old post, however I have just spent some hours dialing in my transient fuel on my L31 Marine intake on my 383 using a P59 with a 12592618 OS.

    Here is what I have found. HP Tuners does not have all the tables that need to be used to correct the transient fueling defined. The reason the results people seeing are somewhat unpredictable, is because they only have what appears to be a few multiplier table defined. There are like 10 transient fuel tables all together.

    We are missing several tables on most P59 operating systems including Impact and Evaporation tables for both Closed Throttle and WOT, as well as the Throttle Stomp compensation table. There is also a decay table for the Throttle Stomp missing. I also looked at the same stuff in my P01 0411 and it is missing most of the same stuff as well on the HP Tuners Transient fuel tab. The throttle stomp table has a large effect on sudden throttle increases similar to accelerator pump in a carb. The decay table changes how long the added burst of fuel is. I have tuned on both and my tip in no longer goes lean like it was. Still working on a slightly rich tip-out but it have also greatly reduced that. The throttle stomp table functions similarly to the Impact table but is for large TPS transients. Together they function similarly to MAP and TPS AE as well as DE on the older OBD1 stuff. The throttle stomp table gets more transient fuel flowing more quickly than the normal Impact table that has a delay until the MAP changes.

    If HP Tuners would add the correct tables tuning the transients would actually become possible.

    I have also done some more work on my Proportional and Integral 02 sensor settings in closed loop. The engine runs smooth as silk in closed loop now going down the road even with Doug Thorley Tri-Y long tubes and double the factory injector size.
    Last edited by Fast4.7; 03-04-2023 at 01:43 PM.

  12. #72
    Hmm.. I missed that last post I guess. Could explain why I'm having trouble. Wonder if the wild '411 tuners have anything to add?

    Jim
    Last edited by Jim Blackwood; 10-27-2023 at 09:11 AM.