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Thread: E38 maxed out MAF

  1. #1
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    E38 maxed out MAF

    First time tuning a E38 with a supercharger.
    Its cammed 6.2 with LSA blower.
    I got the MAF table almost perfect.. except now im at the 4063 lb/h limit. Is my only option to go Speed density now?

    Thanks

  2. #2
    Tuning Addict 5FDP's Avatar
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    If it's a card MAF you can put it in a larger intake tube.
    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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    Quote Originally Posted by 5FDP View Post
    If it's a card MAF you can put it in a larger intake tube.
    Yea its a card type.
    Larger tube then retune?

  4. #4
    Senior Tuner Ben Charles's Avatar
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    You injector data is off... no way you maxes out a 2000 GSec limit with lsa blower

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  5. #5
    Senior Tuner SultanHassanMasTuning's Avatar
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    ^ yup LSA blower will never max out that maf
    Follow @MASTUNING visit www.mastuned.com
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  6. #6
    Senior Tuner Ben Charles's Avatar
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    Probably show engine tq making 2000+.. should have known right then something is off lol

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  7. #7
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    hum....
    First time with this E38 and first time with HPT. Been using EFI Live for 16 years and im use to the older LS1B PCMs.
    Struggling thru this and looking back over the log/tune i just noticed i made a pretty big mistake.

    I got talked into doing this tune from a friend that his dad passed away and there are alot of unknowns about the setup in this truck.
    But i looked it over and finally got the HPT interface box and the guys laptop. Once i got around the laptop password i started going thru everything. I just noticed they had the injectors data in a none linear slope. So i bet that explains alot right there.

    On the last log it shows really lean in boost and the numbers in that range of the MAF are already maxed out at 4063 lb/h.
    But then again i dont think i ever checked fuel pressure in this truck neither.. Ill have to do that next.

    Anybody interested in doing a email tune? haha
    At this rate it is going to take me forever to get this thing ironed out.

  8. #8
    Senior Tuner Ben Charles's Avatar
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    I PMed you back..
    My vet is losing fuel pressure and just blindly adding to the MAF sensor (which won’t matter Bc fuel system is tapped.

    Plus a lot more to tuning then dialing in MAF

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  9. #9
    I started a thread about this just recently https://forum.hptuners.com/showthrea...-tune-attached
    I was asking about the e38 512 g/s maf limit(512 g/s = 4063 lb/hr)
    this is what I found out:
    vcm scanner maxes out at 512 g/s (4063 lb/hr) for maf PID but has pretty much no max for Dynamic airflow PID
    the max on the maf frequency is 15,400mhz if you have the custom OS patched
    Technically with a wideband, you can tune the maf frequency all the way to 15,400 and if you want to see airflow beyond the maf limit, you can monitor the dynamic airflow.
    I personally went with the 2 bar custom SD OS, and then an actual 2 bar map sensor and have never looked back. hope that helps

  10. #10
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    Good info. I am updating my tune for a SC but want to get it running on the new os with the new injectors and 2 bar map before I get the SC installed.
    When you went to 2 bar os how did you initially populate the 3 new ve tables? I have a 2008 gen 4 E38.

  11. #11
    first i tried inverting the table through excel, as you will see vve to ve has different columns and rows. After that didnt give me what I was hoping for, I simply went to the hptuners tune repository and found another tune similar in year to mine that was already in custom 2 bar SD, and used their map settings, to get the correct flow and shape, and also get it idling and running. It doesn't have to be perfect as you will tune it from there.

  12. #12
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    Quote Originally Posted by Gpargament View Post
    first i tried inverting the table through excel, as you will see vve to ve has different columns and rows. After that didnt give me what I was hoping for, I simply went to the hptuners tune repository and found another tune similar in year to mine that was already in custom 2 bar SD, and used their map settings, to get the correct flow and shape, and also get it idling and running. It doesn't have to be perfect as you will tune it from there.
    Thank you I did have to adjust the columns and rows. I will look for one in the repository. I am not able to see them yet as I need to add the serial number for my device before it will let me in. My hptuners is at my shop.

  13. #13
    Advanced Tuner jsllc's Avatar
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    Actually not true. A VVE can be set to match the VE of SD exactly. Then it just requires the inverse function in Excel and you are done. If your VVE was close. There are some very experienced tuners here that can help point you in the right direction. Just won't do it all for free. Many make their living and well that takes food off the table. They always help though if you are willing to work with them. Your car uses MAF as reference and unless you run out of frequency (doubtful) the dynamic keeps on going. That is what the car uses 100% of the time anyway.

    But there are other gotchas to running boost on a non-boosted OS of an e38.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  14. #14
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    Finally got a fuel pressure gauge hooked up and sure enough when it wants some more fuel the pressure falls off. seen it go down to 20psi the first try. So waiting on a pump to be delivered now.

  15. #15
    Quote " Actually not true. A VVE can be set to match the VE of SD exactly."

    like i stated above the columns and rows have to be changed, stock e38 maxes out at 105 kpa, where the sd custom os which gives you the real VE table goes to 175kpa, the rpm for a stock e38 goes to 7000 and the custom sd os goes to 6800(photos based on 2007 C6Z). That is why you have to change the rows and columns, then paste into excel, then use the inverse function. and all that is dependent on how well they tuned the vve to begin with. Considering most new tuners just tune the maf and leave the vve untouched, the easiest thing for a new tuner to do, who has just converted from vve to a real ve table, is copy and paste from an existing tune, from the repository, and tune from there. I have done it both ways, and just dont see the need to reinvent the wheel everytime, when a lot of people have already put in the long hard work, and thats one of the huge advantages to HPtuners, is the repository.

    2007 e38 stock vs custom sd os, vve vs ve. these are how the tables were on both stock tunes before i changed anything.
    ve vs vve.png

  16. #16
    Senior Tuner eficalibrator's Avatar
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    Quote Originally Posted by Gpargament View Post
    like i stated above the columns and rows have to be changed, stock e38 maxes out at 105 kpa, where the sd custom os which gives you the real VE table goes to 175kpa,
    WRONG

    The stock OS with VVE is perfectly capable of running out to 255kPa. It's just an equation inside the ECU with a series of coefficient inputs. If you put an LS9 MAP sensor on the car, it works fine. The reason some think it stops at 105kPa is that they are only using a 1 bar editor for the VVE tool instead of looking at those same coefficients in a 2 bar editor like they're supposed to. I used my personal twin turbo LS3 (2009 e38) as the demo for my VVE training video HERE. There is almost never a need to swap to a custom OS for most street cars in my opinion.

  17. #17
    Senior Tuner Ben Charles's Avatar
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    Yep just have to edit the Axis! Can custom do it or use the drop down Map Axis hp tuners supplies!

    On boost setups past 255 I’ve either scaled map or depending on how boost is done (linear vs non linear) you can add fuel other then VVE (but I prefer VVE to make it as accurate as possible

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  18. #18
    Advanced Tuner jsllc's Avatar
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    Quote Originally Posted by eficalibrator View Post
    WRONG

    The stock OS with VVE is perfectly capable of running out to 255kPa. It's just an equation inside the ECU with a series of coefficient inputs. If you put an LS9 MAP sensor on the car, it works fine. The reason some think it stops at 105kPa is that they are only using a 1 bar editor for the VVE tool instead of looking at those same coefficients in a 2 bar editor like they're supposed to. I used my personal twin turbo LS3 (2009 e38) as the demo for my VVE training video HERE. There is almost never a need to swap to a custom OS for most street cars in my opinion.
    THANK YOU! Like pushing a bolder up hill.

    VVE/MAF and dynamic can get to 1200HP I know. May have an issue by 1500. I will find out with next blower. It all works fine if not over tuned with BS adds like 2000+ cc injectors for 850hp gas cars.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm