Results 1 to 8 of 8

Thread: 2018 CTS-V unknown fuel cut when spinning?

  1. #1

    2018 CTS-V unknown fuel cut when spinning?

    I am currently working on a V3. Nothing too crazy, ported blower/cam and meth. Made 710whp/800lbft. Only issue I am having is for some reason if it spins in 1st it will not shift to 2nd. I have attached the current tune and a couple logs of it doing it.

    I can see that it is cutting fuel somewhere between 5500-6500 (its inconsistent) even though the rev limiter has been bumped to 7k (for testing.)

    Thanks for your time. braketqlimit.hpl7k rpm.hplstock tq-7k.hpt

  2. #2
    Senior Tuner SultanHassanMasTuning's Avatar
    Join Date
    Nov 2009
    Location
    All Around
    Posts
    3,149
    you got to dial in your torque tables

    no way at full throttle just before 5K your timing is zero and negative which essentially is causing a miss
    Follow @MASTUNING visit www.mastuned.com
    Remote Tuning [email protected]
    Contact/Whatsapp +966555366161

  3. #3
    Thanks for the reply!

    Perhaps you could be more specific on what the problem with them would be? I have a good understanding of how the virtual torque tables work and I do not believe they are the issue in this case. Do you mean a different torque table perhaps?

    The car is triggering fuel cut and rev limit tq management before the rev limit has been reached, which I believe is the main issue.

  4. #4
    Tuner in Training
    Join Date
    Sep 2019
    Posts
    11
    there is torque mnagement type pid somewhere and it will say whats pulling timing, also ur almost doubling your rail pressure versus whats demanded, went and looked at a couple zl1 and zo6 and all stay with desired and vever over roughly 3k psii, ur hitting close to 5k psi with commanded of 2900

  5. #5
    Yes, it says Trans S, fuelcut and Trans T once in a while, those channels are all in the log above. Problem is, they dont say fuelcut when its happening and give random revlimit when the engine is deceling? I noticed the fuel pressure spiking as well, I figure that is because of the unknown fuel cut. When the pressure spikes, the injectors show 0 or low ms, IE fuelcut. Makes sense if there is no where for the fuel to go. Still trying to sort out WHY it is cutting fuel though.

  6. #6
    Advanced Tuner lt1z350's Avatar
    Join Date
    Mar 2014
    Location
    Dandridge, TN
    Posts
    560
    Turn off predicted torque under fuel>cutof dfco can raise the commanded down at the bottom across the board to 2500 and raise the fast torque enable to 6000. That will make the rev limit work more like older ones and not hit unitl what you have set in it. No early fuel cuts or predicted throttle cut. then need to lower the shift points if that doesnt take care of it and I dont see the tcm on the tune so assume its still locked which will have the first gear max torque down at 550 stock I think which your all over that now at this point. Ive seen people work around it but easier to unlock the tcm and raise the limits.
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

    2013 cadillac ats 2.0t Big turbo-gone
    2007 tahoe 5.3 lsa blower on 14 lbs boost 6l80e swap 2009 os
    2017 zl1 a10 big gulp/2 inch headers/ 9.55 lower/ e85/bigger hx /103mm tb / Synergy trunk tank and underhood kit/methanol injection with torqbyte controller and prometh pump / Jokerz performance R&D ported stock blower/ lme cnc heads /GP tuning custom cam. So far 9.30@150

  7. #7
    Advanced Tuner
    Join Date
    Aug 2014
    Location
    Central, LA
    Posts
    737
    Quote Originally Posted by lt1z350 View Post
    Turn off predicted torque under fuel>cutof dfco can raise the commanded down at the bottom across the board to 2500 and raise the fast torque enable to 6000. That will make the rev limit work more like older ones and not hit unitl what you have set in it. No early fuel cuts or predicted throttle cut. then need to lower the shift points if that doesnt take care of it and I dont see the tcm on the tune so assume its still locked which will have the first gear max torque down at 550 stock I think which your all over that now at this point. Ive seen people work around it but easier to unlock the tcm and raise the limits.
    Just to clarify, you're setting the entirety of ecm 12073 to 2500 across the board?

  8. #8
    Advanced Tuner lt1z350's Avatar
    Join Date
    Mar 2014
    Location
    Dandridge, TN
    Posts
    560
    Quote Originally Posted by sevinn View Post
    Just to clarify, you're setting the entirety of ecm 12073 to 2500 across the board?
    yes well I actually have it maxed on my tune. If you do this on a manual it will then rev out and let you attempt to launch it hard. It removes the 4k limit totlaly from it.On the auto I have found it makes it have more of an old style rev limit with out fuel cuts and throttle cuts. So if you have 7k in the rpm it will not hit it unitl it reaches 7k and its more of a timing cut limit like early stuff.
    I looked over this tune a little more there is no vve in it and I mean no values. You need to put that back to stock at a minumum who knows how much that table having all zero in it is skewing the vt and shifting on this thing.
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

    2013 cadillac ats 2.0t Big turbo-gone
    2007 tahoe 5.3 lsa blower on 14 lbs boost 6l80e swap 2009 os
    2017 zl1 a10 big gulp/2 inch headers/ 9.55 lower/ e85/bigger hx /103mm tb / Synergy trunk tank and underhood kit/methanol injection with torqbyte controller and prometh pump / Jokerz performance R&D ported stock blower/ lme cnc heads /GP tuning custom cam. So far 9.30@150