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Thread: Whats wrong with this lean/ rich issue ?

  1. 08-06-2017 #1
    4horseman
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    Whats wrong with this lean/ rich issue ?

    I have been chasing down an issue with a very lean idle. I did boost leak check the car and found a very bad leak at the MAP sensor bung on my ls6 intake. After repairing and rechecking with air pressure and finding no more leaks I started the car and its is running +20 short term fuel trim and rough. Wide band at +19 afr. When coming out of open loop the car stabilizes to 14-4- 14.9 but STFT are in the +20 area.

    When I disconnect the IAT sensor the idle is beautiful but a little rich as it should be showing 13.2- 13.6 on LC1 wideband. When coming out of open loop it stays near perfect stoich but trims are - 7 to - 11 so a bit rich.

    I changed the IAT sensor , made sure it was reading within 10 degrees of ambient but the car still will run lean when IAT plugged in and rich without.

    I am running speed density and methanol so I really need that IAT and do not know what I should be troubleshooting at this point.

    Any help would be greatly appreciated.
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  2. 08-06-2017 #2
    5FDP
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    Post the tune and logs.
    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. 08-06-2017 #3
    4horseman
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    I am using an earlier version of HP tuners . Is that ok? Version 2.24.57
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    Last edited by 4horseman; 08-06-2017 at 08:23 PM.
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  4. 08-08-2017 #4
    4horseman
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    anyone?
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  5. 08-08-2017 #5
    5FDP
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    MAF dtc's are wrong for speed density, they need to be set to MIL on first error.

    What worries me some is that you have closed loop setup around 100 degree coolant temp but you have basically zero o2 sensor functions for a long long time in that first log. It's almost like it doesn't know what do to for a while and it could be because it's waiting for the MAF to fail and then it can enter closed loop.

    Also what map are you using?

    Most of the 2 bar map sensors are 210/10.33 for their settings.
    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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  6. 08-15-2017 #6
    stroker007
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    Upload stock tune on the ecu ... if you still get same problem ... replace ecu
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  7. 08-16-2017 #7
    4horseman
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    My car is showing p0103 maf sensor code and is going into speed density. The timing is running right with the low octane spark table. I am using a GM 2 bar map sensor. We have already checked the voltage at the harness and the sensor output. I will change to set for MIL on first error and see if that helps. Thanks
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  8. 08-16-2017 #8
    4horseman
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    can not do that. Stock tune wont work on this force inducted and cammed motor using 1 bar
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