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Thread: 2012 Camaro SS 6.2 LS3 in restomod - No AFR reading and low power

  1. #1
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    2012 Camaro SS 6.2 LS3 in restomod - No AFR reading and low power

    Hi!

    I am writing this post on behalf of my dad.
    He has a old GMC Pickup that was restomodded back in 2016 using a 6.2 LS3 from a manual 2012 Camaro SS, and a wire harness + ECM / TCM / O2 sensors from PSI Conversion in NJ.
    The installation was very smooth and the car ran right away, but recently we started running some 1/8th mile to get me used to dragracing in preparation for another car we are building.
    While running we noticed that the ET and speed was very low compared to what we expected for 430HP / 1500kg , and my dad has his friend check the car with HP Tuners.
    The car was showing almost zero degrees ignition advance on WOT, and his friend noted that there was probably 150 or so less HP than stock.
    He also noted that in HP Tuners there is no AFR reading shown.

    He tried changing up some things in the tune, and we were able to get it to run much better, but with some hesitation due to knock retard at WOT high load.
    Am i right to assume that the AFR should be shown inside HP Tuners if it is actually being read, and that the ECM would run in Open Loop in the absence of AFR readings, which could perhaps explain why it's so sluggish?

    We have tried everything i can think of including checking that the o2 sensors are providing voltage ( which they do, it fluctuates a lot though, anything between 0.1 and 0.9 volts on WOT) and verified all spark plugs/ingition cables/coils etc.
    So basically, the cars starts and runs nicely and smoothly, but it feels like there is almost no power at all on WOT.

    Does anyone have some tips and tricks on what we can do?
    I should probably note that i have zero experience with Hp Tuners, but we do have my dads friend who knows the ropes.
    Attached is a log from some test runs.
    Thank you in advance.
    pickis.1 (1).hplpickis.2 (1).hpl

  2. #2
    Advanced Tuner jsllc's Avatar
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    Without the tune no way to tell. There is no WB on a GM 6.2 so there is no AFR. There should be stock O2 sensors but these are not wide-band. OL or CL is tune dependent. Would need a complete list of mods for the motor as well.
    Last edited by jsllc; 08-06-2019 at 02:41 PM.
    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

  3. #3
    Senior Tuner Ben Charles's Avatar
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    I do a lot of resto mod tuning... post the tune and I’ll take a look

    Email Tunes, [email protected]
    96 TA Blown/Stroked, 4L80E/Fab 9
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  4. #4
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    Quote Originally Posted by Ben Charles View Post
    I do a lot of resto mod tuning... post the tune and I?ll take a look
    Hi!
    Thank you for the reply.
    Attached is the tune we were provided by PSI after contacting them for troubleshooting, but this tune ran identical to what we already had on the box from when we bought it.
    No mods on the engine, only difference compared to the car it came from is 4L65E trans instead of manual, and no cats, just headers into pipes with a muffler each PCM-1008 6.2 4L60E NONVVT LS3 BOS 2PIN 430HP HELENA STEFANSSON 430HP TUNE.HPTat the end.

  5. #5
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    Quote Originally Posted by jsllc View Post
    Without the tune no way to tell. There is no WB on a GM 6.2 so there is no ARF. There should be stock O2 sensors but these are not wide-band. OL or CL is tune dependent. Would need a complete list of mods for the motor as well.
    Hi!
    Thank you for the reply, please see the reply to Ben Charles below

  6. #6
    Advanced Tuner jsllc's Avatar
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    Quote Originally Posted by ts1993 View Post
    Hi!
    Thank you for the reply, please see the reply to Ben Charles below
    After a brief look there is nothing REALLY bad but, some things sure do not seem right in the tune. You do not log enough data to tell the issues. Need to make sure you have all of these added or in your log. If you do not have an alcohol sensor skip those.
    8-8-2019 8-41-33 AM.jpg
    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