Results 1 to 19 of 19

Thread: TQ tables on H/C CTS-V LT4

  1. #1

    TQ tables on H/C CTS-V LT4

    I have a 16' CTS-V with the LT4. Under WOT she's sloooow. The car has way more in it. I've had multiple Gen 3,4 cars that I have tuned but these Gen 5's I just don't fully understand. Wondering if ya'll could take a look and give me some pointers. I have the car idling good and driving pretty good. VE is within 5% or so and MAF within 3%. When I go WOT the engine sounds and feels held back but throttle stays open at 84% while Accel is 100% and no Tq Mgmt that I see along with 0.82 ish lambda. It is seeing some knock with very little timing. Also think boost is low for the pulley set up but maybe thats just due to the blower being so small on the LT4's.
    I believe the power is being held back. I'm monitoring everything I can think of for TQ but I don't see a correlation and need help understanding what to look at so I know what to adjust.

    Log 23-09-05 19-53-12.hpl
    Tune TUNE-6-16Z06-dd-1-vve-dfco-1.hpt

    Mods are- built motor with slightly more compression (10.7:1), ported heads, stage 1 cam (BTR's newest boost cam 38% lobe 217/242), long tubes, no kittens, Big Gulp intake, 2.3/9.1 pulleys, 93 octane but will be tuning with meth once I get the 93 tune right. Also before I do damage I'm adding a voltage booster to the fuel pump because the fuel pressure is getting low and its not even making any power yet.
    Attached Images Attached Images
    Last edited by Racerbox77; 09-06-2023 at 05:34 PM.

  2. #2
    Tuning Addict
    Join Date
    Jan 2015
    Location
    Franklin, NC / Gainesville, Ga
    Posts
    6,819
    Get the low side fixed and check the plugs and wires on bank 1 as it appears to be misfiring. I just looked at the log, not the tune.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  3. #3
    Senior Tuner
    Join Date
    Nov 2006
    Posts
    2,751
    Agreed.. go after whatever is causing the low lift pump pressure.
    Tuner at PCMofnc.com
    Email tuning!!!, Mail order, Dyno tuning, Performance Parts, Electric Fan Kits, 4l80e swap harnesses, 6l80 -> 4l80e conversion harnesses, Installs

  4. #4
    Quote Originally Posted by GHuggins View Post
    Get the low side fixed and check the plugs and wires on bank 1 as it appears to be misfiring. I just looked at the log, not the tune.
    Thank you so much GHuggins! I wasn't logging misfires but will now. I ohm'd out the wires and found one bad one.
    Quote Originally Posted by Alvin View Post
    Agreed.. go after whatever is causing the low lift pump pressure.
    Alvin Are you talking about the in tank pump being weak? Isnt that normal and I need to upgrade with a boost-a-pump?

  5. #5
    Tuning Addict
    Join Date
    Jan 2015
    Location
    Franklin, NC / Gainesville, Ga
    Posts
    6,819
    The DSX aux kits are common for these. You can also upgrade the in tank. I've got two customers I'm working on right now both running the aux pump kit with BAP's on the primary's. Both make good power with a whole lot of mods. I think one of them even upgraded the primary and running a bap on it too. They don't have any fuel supply issues.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  6. #6
    Quote Originally Posted by GHuggins View Post
    The DSX aux kits are common for these. You can also upgrade the in tank. I've got two customers I'm working on right now both running the aux pump kit with BAP's on the primary's. Both make good power with a whole lot of mods. I think one of them even upgraded the primary and running a bap on it too. They don't have any fuel supply issues.
    So I found a bad wire on bank 1. Swapped it then went for a drive logging misfires. I'm logging #7 missing.
    How can I view my log I posted here but monitoring misfires like you did, to compare if it was 7 before the new wire?
    Thanks
    Last edited by Racerbox77; 09-06-2023 at 08:33 PM.

  7. #7
    Tuning Addict
    Join Date
    Jan 2015
    Location
    Franklin, NC / Gainesville, Ga
    Posts
    6,819
    I only know it was missing on that bank in general. Not exactly which one was missing. It was shown by your wot pull where the O2 was nose diving on the one bank whilst the other was staying steady.

    As long as you're logging misfires and they're set up to report in the tune you should be able to log which cylinder is missing if one still is. Usually when these misfire it's the plugs themselves. Boost and fuel with high cylinder pressure makes it hard for the spark to cross the gap.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  8. #8
    bank 1 is screaming. check the misfire thats going on. if plugs and plug wires are good, you're most likely having an injector issue. you need a low side aux pump. whats going on with that high pressure pump? seems super low. i've not checked the tune nor paid more attention to the log but caught those i mentioned.
    Specializing in calibrating GM vehicles. HPtuners and HolleyEFI

    Remote tuning services email [email protected]
    instagram: tunedbymmt


  9. #9
    Quote Originally Posted by MeshaalMMT View Post
    bank 1 is screaming. check the misfire thats going on. if plugs and plug wires are good, you're most likely having an injector issue. you need a low side aux pump. whats going on with that high pressure pump? seems super low. i've not checked the tune nor paid more attention to the log but caught those i mentioned.
    I did find a bad wire on bank 1. I need to figure out if there's anything else wrong so I'm no logging misfires.
    What pressure should the Hi pressure pump be at when wot?

  10. #10
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    3,278
    Quote Originally Posted by Racerbox77 View Post
    So I found a bad wire on bank 1. Swapped it then went for a drive logging misfires.
    Quote Originally Posted by Racerbox77 View Post
    I'm logging #7 missing.
    Was the bad wire on cyl. 7? If it's still logging as a misfire I'd be doing a leak down test on the cylinder.

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]

  11. #11
    Quote Originally Posted by edcmat-l1 View Post
    Was the bad wire on cyl. 7? If it's still logging as a misfire I'd be doing a leak down test on the cylinder.
    Luckily it's a cracked porcelain plug. New plug ordered.
    What do you mean about the hi pressure fuel? What is it supposed to be @ wot? I see requested is similar to delivered. I have noticed the low side needs help asap. I'll be upgrading that before I continue any wot pulls.

  12. #12
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    3,278
    Quote Originally Posted by Racerbox77 View Post
    Luckily it's a cracked porcelain plug. New plug ordered.
    Good deal. Any miss on cyl 7 or 8 is scary.

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]

  13. #13
    I've got the misfire fixed. Thank you gentlemen!
    Still being restricted by TQ Mgmt somehow. See pic.
    Also I know its hot but only 11 psi? A similar set up on the LSA engine would be 15+ psi
    20230907_151948.jpg
    Last edited by Racerbox77; 09-07-2023 at 02:25 PM.

  14. #14
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    3,278
    Quote Originally Posted by Racerbox77 View Post
    I've got the misfire fixed. Thank you gentlemen!
    Still being restricted by TQ Mgmt somehow. See pic.
    Also I know its hot but only 11 psi? A similar set up on the LSA engine would be 15+ psi
    20230907_151948.jpg
    Good deal on the fix.

    Last 2 rows of the DD tables should be your key to keeping the blade open.

    Yeah the GEN5 blowers are pretty small but boost does sound low for the pulleys. What's your altitude?

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]

  15. #15
    Tuning Addict
    Join Date
    Jan 2015
    Location
    Franklin, NC / Gainesville, Ga
    Posts
    6,819
    Normal for these blowers to fall off unless really spun up, BUT these things are notorious for belt slip. Won't show up anywhere other than airflow measurements. Won't show that much with the psi loss unless it's pretty bad. Just look for rubber around the water pump and supercharger snout area not to mention tensioner movement. Tensioner should be close to the middle - has to have as much movement for decel as accel. Bet it's slipping if it hasn't been changed in a year or two.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  16. #16
    Quote Originally Posted by GHuggins View Post
    Normal for these blowers to fall off unless really spun up, BUT these things are notorious for belt slip. Won't show up anywhere other than airflow measurements. Won't show that much with the psi loss unless it's pretty bad. Just look for rubber around the water pump and supercharger snout area not to mention tensioner movement. Tensioner should be close to the middle - has to have as much movement for decel as accel. Bet it's slipping if it hasn't been changed in a year or two.
    I think you're right about the belt slip. Its a Griptech pulley and a new Green belt. Have you had good luck with the DSX tensioner?

  17. #17
    Tuning Addict
    Join Date
    Jan 2015
    Location
    Franklin, NC / Gainesville, Ga
    Posts
    6,819
    Not on these, but they are adjustable. If you have a new right length belt and that pulley it shouldn't be slipping. Again if it's the right length.

    It'll show if it's truly slipping, but will also most likely be money wasted since it'll snap, but you can put a gates blower specific belt on it. It'll never slip, but it'll snap like a pretzel if anything at all isn't right which seems to happen a lot on these for some reason. I think it's just a design flaw with the belt routing setup from factory once you start changing pulley sizes.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  18. #18
    Wanted to update. After a lot messing around found out the stock muffler was clogged. Previous owner blew up the engine so must have had something in there. Crazy enough. Swapped the stock muffler with a lighly used oem and picked up over 100 whp on the dyno. Ended up making 800whp on E60 and meth

  19. #19
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    3,278
    Nice find and fix. BP will definitely kill power. One of my favorite tools is my little 65 dollar BP gauge.

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]