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Thread: NEED HELP... LS3 Swap 6.2 Gen 4 Grand Sport Corvette

  1. #1
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    NEED HELP... LS3 Swap 6.2 Gen 4 Grand Sport Corvette

    Greetings. I am new to HP Tuners and looking for some help. I am working on a LS3 Swap. The engine is a 2011 Corvette Grand Sport 6.2 Gen. 4. The control module is a E38. The E38 is out of a 2011 Grand Sport Corvette but not the same donor car as the engine.

    The wiring harness is a Painless Wire Harness.

    I have disabled VATS 1 & 2 in HP Tuners.

    The engine will crank but will not start. It appears I am getting spark and fuel to the rails.

    Any ideas why it is not starting? I appreciate any direction which to try next.

    If you can help me and it gets this engine running, I would be happy to compensate a reasonable amount of money for your time and assistance.

    Thank you.
    Last edited by Vintage Steel; 03-26-2020 at 01:52 PM.

  2. #2
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    People are probably going to want to see your tune file and links for more detail on what you are using. I?m no expert but installed a spare 2010-2013 e38 ecm with a Factory corvette tune and anti theft disabled on an already running swap with a 2008 5.3. It did start and run (although not well) so I?d say ensure that the edits you made actually took place, then check fuel pressure and wiring.
    Last edited by Carbon; 03-26-2020 at 03:03 PM.

  3. #3
    Senior Tuner Ben Charles's Avatar
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    Did you perform a write entire?

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    Quote Originally Posted by Ben Charles View Post
    Did you perform a write entire?
    Yes, I performed a write entire.

  5. #5
    back to basics: doubt its vats- What is powering your fuel pump"- do you have fuel pressure?
    are we sure we have spark- visually checked, and fuel- (noid light on injector harness) and good fuel pressure,?
    the fuel/injector firing /fuel missing part can be tested with shooting a bit of brake cleaner (flamable kind ) into intake . not too much about 1.5 -2 seconds from aerosol can as we don't want damage or intake pop.

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    Quote Originally Posted by goodwrenchdave View Post
    back to basics: doubt its vats- What is powering your fuel pump"- do you have fuel pressure?
    are we sure we have spark- visually checked, and fuel- (noid light on injector harness) and good fuel pressure,?
    the fuel/injector firing /fuel missing part can be tested with shooting a bit of brake cleaner (flamable kind ) into intake . not too much about 1.5 -2 seconds from aerosol can as we don't want damage or intake pop.
    I do have spark. I have visually checked. However, in pulling out the plug, the plug is dry. Thus, it may not be getting fuel. I am getting fuel to the rail. I can use the bleeder valve and it spits fuel. I have not checked the fuel pressure yet at the rail. I will work on that in the morning. What pressure should I have at the rail for the 6.2 LS3? Also, I will have to go buy a noid light kit to check the injectors.

    The odd thing is, I am not getting any movement in the tachometer when cranking. Do you think the crank position sensor would cause the engine to not even fire? Or, the tach reading may be another issue all by itself?

    I did try the brake cleaner trick. It did try to fire for a second.
    Last edited by Vintage Steel; 03-26-2020 at 07:54 PM. Reason: spelling

  7. #7
    Quote Originally Posted by Vintage Steel View Post
    I do have spark. I have visually checked. However, in pulling out the plug, the plug is dry. Thus, it may not be getting fuel. I am getting fuel to the rail. I can use the bleeder valve and it spits fuel. I have not checked the fuel pressure yet at the rail. I will work on that in the morning. What pressure should I have at the rail for the 6.2 LS3? Also, I will have to go buy a noid light kit to check the injectors.

    The odd thing is, I am not getting any movement in the tachometer when cranking. Do you think the crank position sensor would cause the engine to not even fire? Or, the tach reading may be another issue all by itself?

    I did try the brake cleaner trick. It did try to fire for a second.
    Without knowing the specifics on your harness, If you are going to troubleshoot the cam and crank sensors the one thing I'd suggest verifying that they are pinned out correctly, and getting a 5v reference and not 12 if you are using 58x sensors.

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    If you have a more or less matching ECM and tune, what happens when ?write entire? is used for making edits?
    Last edited by Carbon; 03-27-2020 at 07:10 PM.

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    Quote Originally Posted by Carbon View Post
    If you have a more or less matching ECM and tune, what happens when ?write entire? is used for making edits?
    It is the matching ecm and tune, I kept all the tune info the same. I simply disabled VATS 1 & 2 and changed the transmission setting from auto to manual. Then wrote entire.

  10. #10
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    The auto to manual doesn't work like that just so you know. I'd switch it back to auto for the now.

    If you truly wanted this file to be a manual you'd need to flash it with a GM tool to a manual file from the get go.

    It's helpful if you post the tune file and logs of you starting it too, just so we can see what is going on.
    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.

  11. #11
    I know it wasn't super clear at first how to use the vcm scanner- so here goes :
    open vcm scanner. Then at top- vehicle -> connect. press red record button and then while its recording start cranking. Save it and then post that file....
    do you have a cranking rpm in vcm scanner? if not there is a problem with crank sensor/circuit. and that would explain the no injector fire. I personally would also like to see the cam sensor counts (but you need to add that channel to vcm)
    do you have any dtc setting after cranking?

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    Update...

    I replaced the cam sensor and crank position sensor. Disabled the "starter fault checks". Also disabled (in the clutch position sensor area) "clutch interlock".

    The engine will fire-up now. It runs for about 2 seconds and dies.

    I double checked for VATS and the HP Tuners is showing VATS 1 & VATS 2 disabled.

    If I can figure out how to save the scan and post it on the forum, I will.

    Any other direction at this point?

  13. #13
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    Quote Originally Posted by 5FDP View Post
    The auto to manual doesn't work like that just so you know. I'd switch it back to auto for the now.

    If you truly wanted this file to be a manual you'd need to flash it with a GM tool to a manual file from the get go.

    It's helpful if you post the tune file and logs of you starting it too, just so we can see what is going on.
    Here are the codes HP Tuners is reading...
    LS3 6.2 Gen 4 CODES.jpg

  14. #14
    first and last are only real problem dtc. (all other are emissions equipment etc) - is that accelerator pedal the same that came on car with that ecm? that code will imidiately put you into reduced power mode when it sets. clear them and restart to see if they re set.
    look at your map value - should be around 14.8psi (100kpa) engine stopped and drop to 4.5-5.5psi idle.

    You save the log by pressing the little square disk symbol on the vcm scanner toolbar or "log file"-> "save as " then give it a name and remember where its saved (usually in documents- hptuners-logs and tunes -givenname.hpl.) the tune will also be there as given name.hpt -if you post those it will be easier to figure out if something is missing or wacky.

  15. #15
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    Second Update...

    I have the ls3 6.2 fired up and running. The problem seemed to be in the tune I was trying to write. I wiped the tune clean and started over. The problem was in the single bar vs double bar tune. I think I may have clicked the "enable double bar" on the first write entire. Nonetheless, on the new write entire, I started with the single bar. She starts and idles fine. On a side note (this may help someone later down the line)… after I got the engine running, it would not shut off with the ignition key. I was getting feedback from somewhere. I first checked the alternator, the ignition wiring, the relays, then the fuse block to see if any metal shavings from drilling holes may have fallen into the fuse block causing a short. I could not track it down. I solved the problem by installing a small diode at the key cylinder wiring which prevented the feedback. I hope this may help someone down the line.

    However, I am still have some problems and need some help. The engine idles like the thoroughbred she is. But now, I have no response from the fuel pedal. It is a drive by wire system. In HP Tuners, the program registers the movement of the gas pedal through the computer scan but the engine does not respond? Can anyone point me in the right direction on what to check? The gas pedal is supposedly out of the same car but I cannot say for sure. Where do I start?

    Thank you in advance for any assistance and advice.
    Last edited by Vintage Steel; 03-30-2020 at 06:55 PM. Reason: spelling

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    If you are running a corvette tune then the wiring in your Painless harness to your corvette pedal should be a corvette pinout. A lot of swaps use another tune but with a corvette pedal and have to switch pins around.
    Out of interest, what are you running this swap in? Looked at a stock C6 file vs GS stock file and looks like the spark table is bumped up in the GS.

  17. #17
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    Quote Originally Posted by Carbon View Post
    If you are running a corvette tune then the wiring in your Painless harness to your corvette pedal should be a corvette pinout. A lot of swaps use another tune but with a corvette pedal and have to switch pins around.
    Out of interest, what are you running this swap in? Looked at a stock C6 file vs GS stock file and looks like the spark table is bumped up in the GS.
    Thank you for the response. I will check the pinout as suggested.

    The swap is going into a 1961 Scout. It is a rare factory 2 wheel drive scout. It is a high end build. You can google "unbound" scout. The one we are building now is "unbound II".

    As far as the tune, it should be the factory 2011 GS tune. The e38 is from a 2011 GS and we did not change anything.

    I will update again once the pinout is checked. Thank you again.

  18. #18
    Feels like i just went through this .... that is the gas pedal thingy. Any how.... if you need pinouts as far as interchange between gen 4 pedals ..... GM switched out connector circuits positions between platforms- while keeping pedal specs similar on gen 4; request and i will try to provide input/schematics.

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    Quote Originally Posted by goodwrenchdave View Post
    Feels like i just went through this .... that is the gas pedal thingy. Any how.... if you need pinouts as far as interchange between gen 4 pedals ..... GM switched out connector circuits positions between platforms- while keeping pedal specs similar on gen 4; request and i will try to provide input/schematics.
    Yes, please provide the input/schematics. Thank you.

  20. #20
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    Quote Originally Posted by goodwrenchdave View Post
    Feels like i just went through this .... that is the gas pedal thingy. Any how.... if you need pinouts as far as interchange between gen 4 pedals ..... GM switched out connector circuits positions between platforms- while keeping pedal specs similar on gen 4; request and i will try to provide input/schematics.
    Goodwrenchdave, no need for the schematics now. I called painless wiring. I had to switch two of the wires on the pedal end and now everything is working like the pure thoroughbred this LS3 is!!!

    Thanks to all who had input and/or suggestions.