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Thread: Can't Bring MAF Back On-Line After SD Tuning

  1. 10-12-2020 #1
    HATEHPTUNERS
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    Can't Bring MAF Back On-Line After SD Tuning

    Like the title says, I've got an LS Swapped '95 Step Side truck. Has a '99 4.8L engine, and PCM in it. When I got the truck, it had a small motorcycle style air filter clamped directly to the TB. It was TOO SMALL and also it had the MAF too close to the throttle body, and it was sucking radiator heat right into the engine.

    I swapped in an after-market cold air intake. I then went to tune it. I shut everything off necessary to SD tune it.. However, even with everything turned off in the tune, the MAF was STILL on-line.. The MAF refused to shut off.. I know.. It sounds crazy.. Here's the list of what I changed to try and disable the MAF; Engine>airflow>dynamic>dynamic airflow> Hi RPM Disable set to 100, high rpm hyst. set to 50, On that same window I set the hi/lo RPM thresh to "0", Under FUEL>OXYGEN SENSORS>CLOSED LOOP ENABLE-SET temps to 285 across the board, I then set the drop down tab on LTFT to DISABLED, and changed the MIN ECT to 285 and MAX ECT to 100, OPEN LOOP/BASE>OPEN LOOP>EQ RATIO TABLE changed entire table to 1, and also set the STFT OPEN LOOP tab to DISABLED. Left my POWER ENRICH alone. Turn off catalyst protection, turn off DFCO, under engine diag I set AIRFLOW to factory 14000... Set the first 3 MAF DTC's to SES (checked) and MIL on first error.

    With those changes I burned the tune and STILL the MAF was working! I know this because I kept getting really screwy #'s for the VE TABLE and when I tried to make changes to the VE table, the very next log was giving me the exact same #'s as the previous log-indicating NOTHING had changed for the table that the engine was actually running on... I finally decided to just unplug the MAF.. BINGO! I was then able to attempt to tune the SD table.. However.... This year vehicle has a PRIMARY and a SECONDAY SD table.. I did not want to fool with it so I just updated to the SPEED DENSITY ENHANCED (RTT) that was available... I then had ONE VE table, and I was able to tune it rather quickly and get everything within 2% +/-... The problem now... Is that I can't get the MAF to work... Literally.. I've tried EVERYTHING and if I even so much as plug the MAF sensor in, while I still have the tune in SD mode-with everything shut off-it immediately kills the engine. If I try and shut SD mode off in the tune and switch it over to just running off the MAF-the engine WILL NOT RUN/IDLE. I tried logging afr error with my wide band and it just keeps giving me STUPID #'s that when placed in the MAF Calibration table make NO CHANGES. I tried and tried to change the maf cal table to no avail. My wideband was showing me that I was SUPER LEAN-but there is nothing I can do to fix it.. The computer/engine is NOT following the MAF calibration table at all.. Before I just call it a SD tune, and leave it the F alone... Can anyone tell me what I screwed up?

    Any help will be much appreciated.
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  2. 10-12-2020 #2
    5FDP
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    Setting the dynamic airflow high rpm disable to 100rpm is wrong for speed density tuning. Make sure to read the table and how it works. Setting it to 7,000rpm would be what you want. And the MAF must be failed in the tune via the engine diag tab. The MAF fail high hz must be set to 0hz and the 3 MAF dtc's to MIL on first error.

    The MAF will still reported data so long as it's plugged in but if code P0103 is active it's in speed density mode with the MAF failed. Ideally the MAF should not be logged when speed density tuning. Also you can't unplug the MAF if the IAT is built into the MAF.

    You could always go back to the stock tune with the VE table you make in this speed density tune to see if it works any better.
    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.
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  3. 10-12-2020 #3
    HATEHPTUNERS
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    Please let me know if I've got something set up incorrectly in this tune. I will be trying it here in just a minute.
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  4. 10-12-2020 #4
    HATEHPTUNERS
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    I looked back at the tune I was using for SD tuning. HI RPM DISABLE was set at 4000. The SD tune is PERFECT. Needs nothing. It was showing 14.5-14.9 across all RPM ranges from idle all the way up to 4000. I was hand blending the entire table to get it that close. I just need to get the MAF back up and working, if that is possible.

    I can't go back to the "stock tune" because I updated the OS with the Custom SPEED DENSITY ENHANCED. I guess I could burn another licensed tune from my catalog onto this PCM and then just make the necessary changes to mirror the important tables. So much work. I was hoping it would be something simple.
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  5. 10-12-2020 #5
    HATEHPTUNERS
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    Yep.. Fast trip for me... The ENGINE IS NOT RUNNING ON THE MAF!!!! I can put any #'s you want into the MAF CAL table and it has NO BEARING AND WILL MAKE NO CHANGES according to my wide band.. I just ran a quick log, posted below... Based on that I added 20% (1.20) across the ENTIRE MAF CAL table... Ran the log again... Exact same #'s as before. So then, for giggles, I did a 50% fueling increase across the board (1.50) just to see if my WB would register the change.. Nope.. No change. The tune is NOT running on the MAF CAL table. I have no idea what table it's running off of... But it is not the MAF CAL table.

    Should I just burn another complete stock tune from another vehicle, and then copy over my VE table and see how that one goes? I think changing to the CUSTOM SPEED DENS ENHANCED tune has screwed something up.. specifically my MAF! Ha! ha! Ha!
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  6. 10-12-2020 #6
    5FDP
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    So you didn't save your stock tune?

    That would be a mistake.
    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.
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  7. 10-12-2020 #7
    HATEHPTUNERS
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    Log taken after 50% global increase of MAF CAL table.
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  8. 10-12-2020 #8
    5FDP
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    Some say the RTT speed density enhanced OS will disable the MAF, been a while since I could test that again. I've used the MAF on 2 bar OS's before with larger MAF's with boost. The newer computers allows for MAF/VE on speed density OS's too.
    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.
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  9. 10-12-2020 #9
    HATEHPTUNERS
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    Yep.. Fast trip for me... The ENGINE IS NOT RUNNING ON THE MAF!!!! I can put any #'s you want into the MAF CAL table and it has NO BEARING AND WILL MAKE NO CHANGES according to my wide band.. I just ran a quick log, posted below... Based on that I added 20% (1.20) across the ENTIRE MAF CAL table... Ran the log again... Exact same #'s as before. So then, for giggles, I did a 50% fueling increase across the board (1.50) just to see if my WB would register the change.. Nope.. No change. The tune is NOT running on the MAF CAL table. I have no idea what table it's running off of... But it is not the MAF CAL table.

    Should I just burn another complete stock tune from another vehicle, and then copy over my VE table and see how that one goes? I think changing to the CUSTOM SPEED DENS ENHANCED tune has screwed something up.. specifically my MAF! Ha! ha! Ha!
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  10. 10-12-2020 #10
    HATEHPTUNERS
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    Yes, I saved the ORIGINAL tune before I did the ENHANCED SPEED DENSITY OS... I can burn that one back in, but it has TWO VE tables.. I guess I gotta do it though.

    I'll just have to use the data from my current VE table, and blend it back into the original tune. Fun!
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  11. 10-12-2020 #11
    HATEHPTUNERS
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    Some say the RTT speed density enhanced OS will disable the MAF, I believe this is what has happened. I'm going back to the Pre-speed density tune to see if I can find some joy. Wish me luck!
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  12. 10-12-2020 #12
    5FDP
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    Blending the VE back in will take 5 minutes. Just copy the matching rows over and smooth the table, real simple just more work is all.
    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.
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  13. 10-12-2020 #13
    HATEHPTUNERS
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    Yes sir. I went back to original tune, blended the new single VE table over to the dual tables, disabled SD, fired it up, and was getting good data immediately. The MAF is working now! It was something in that ENHANCED tune. I did a quick idle to 3500 (P/N) log, and then increased the entire table 10%. It puts me +/-5% on most cells. I will drive it more tomorrow to finish the MAF tune.

    5F-thank you for your help! You rock! I sent you a PM on another deal I'm working on...
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  14. 11-03-2020 #14
    RustyC
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    I am a new tuner and had similar questions about the primary and secondary tables. My scanner log matches my primary table. I copy the log error and correct (multiply %-half) my primary table in my tune. Then I copy the even rows of the primary table (20,40,50,60,70,80,80,100) one at a time and paste into my secondary table. Write calibration, log. Rinse and repeat as needed.
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  15. 11-03-2020 #15
    cvwinton
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    That's correct, when MAF is disabled you will actually be referencing the secondary table so you need to make sure they both match as you are doing.
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