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Thread: Need help with trans tune 99 C5

  1. #1

    Need help with trans tune 99 C5

    Just purchased 99 Maggie SC C5 with many "supposed" upgrades. long story short is that I was misled.
    Car was supposed to have z06 rear with 3:42 but original pumpkin looks original with 3:15 gear tag
    Trans went out after a few days of normal driving 3-4 gear slip but apparently had been freshened up with some high quality parts verified by the current builder.
    Had trans rebuilt with a new Yank SC 3000 stall converter. Car was shifting very hard like before but felt good with no slipping.
    I was very easy on the new trans and TC doing no full throttle or launches until 250 mile break in.
    Never made it that far..... same symptoms showed up again as driving easy and starting to slip in 3 and 4.
    I had not changed anything in the tune because I was being easy until break in plus I'm just now learning.
    Would someone please look at the tune?? The trans is supposed to be built for +600 ft lbs and have a 1 yr warranty but trans rebuilder is wanting tune looked at first. Old tune should have been for stock TC I believe.
    Attached Files Attached Files
    Last edited by; 09-23-2023 at 12:14 PM.

  2. #2
    Advanced Tuner
    Join Date
    Mar 2009
    Andover, MN
    Shift times and pressures look like it would shift hard lol. I didn't see much TQ Management though. 4l60 wont survive long without some sort of torque management. Usually you break hard parts but it still stands. 600ft lb 4l60? That has to be pretty much "fully built?" Billet shafts, sonnax 3-4 smart-tech shell, etc.

    Also, Tune your VE and MAF, they are pretty hacked.

  3. #3
    I?m very overwhelmed with all the parameters in these tunes. I?m thinking about loading a stock tune for the transmission and gently going from there. It shifted very hard (too hard for me). If I do this what do I have to tweak. I just need to make sure that it is not the tune causing the trans to slip before he will look at it. I was so easy on the rebuild that I?m sure that something was missed.
    I will have to try and look at those maf and VE tables once I can figure them out. The plan was to have it Dyno tuned but trans started acting up before I could get there. It?s a 3 hr drive.
    I wanted to get a good solid tune for both.
    Any help would be very much appreciated

  4. #4
    Join Date
    Dec 2022
    Share a scan if you have one. The VE table is all over the place and the MAF is rough. If the MAF is too far off it can cause the hard shifting similar to SD tuning.