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Thread: 5l40e issues Solstice GXP

  1. #1

    5l40e issues Solstice GXP

    I was tuning a friend's gxp yesterday and I noticed I could not log the vehicle speed on the VCM scanner. I tried adding the channel and nothing. All speed channels added from TCM and ECU and get nothing.

    Another problem is before I tuned the car sometimes it would not shift into 3rd and instead just stay at 6k rpm until you let go of the gas pedal and then it shifts. After checking all the tables and adjusting shift points it will still do this randomly. I made sure all the shifting speeds match from table to table. I noticed it only happens when in competitive mode though. But last night it did a new one at wot without comp mode, the car took off from a dig and as soon as it reached 60mph the car did not shift or accelerate any further. It was as if the was a speed limiter at 60 mph. I removed all limiters prior to that so no idea what is causing the issues.

    My laptop was low battery last night so I don't have a log but today we are giving it another go and will log hoping to get the issue logged this time.

  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
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    first thing to do is save all your current work and perform a write entire of the factory file. If the problem still exists then you need to inspect for mechanical and electrical issues.
    if it doesnt exist then you made a change somewhere to a table that has caused an adverse reaction. typically somewhere around 60 mph is where we see REP mode max allowed speed. I would analyze the torque management corrections you made carefully double checking each tables description. some table work in reverse.

    when you get the chance post a tune and log file if you still haven't figured anything out.
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
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  3. #3
    Thanks, I did read every description on the torque management tables. One time a did a Silverado and it couldn't do a burnout because I accidentally set it to reduce torque 100 percent lol.

    The car wasn't doing it anymore after setting the shift points right. But then yesterday running it at the local track, it was trying to shift at 65 to 3rd gear when I have it set to 55. And they shifting to 4th I set 75 and it wants to go over 80 before it shifts. The earlier tonight my friend said he checked for a boost leak and after fixing it the car shifted at the right speeds and has not limited or tried to shift higher than set. Could it be the TCM protecting the trans because of the boost leak? Tomorrow I will be flashing it as a write entire and hope it gets rid of the issue.

    Any reason I can't read the vehicle speed though? It would be easier to determine what mph to set if I could log it. I'm also thing it could be the vss but the speedometer in the car is working.

  4. #4
    Senior Tuner cobaltssoverbooster's Avatar
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    it could be input load protection. sporadic input data really does some weird things so getting the sensor to read properly really helps out. if the torque calculation jumps wildly it is a possibility that the trans shifts out of gear or holds a gear to maintain a more favorable input load.
    im not sure why vss is not reading. it is somewhat of a concern though as you already have that feeling. its possible a calibration was performed under low voltage and thus suffered from corruption. performing a write entire with the battery charger connected to guarantee voltage and all accessories off should return the vehicle to a completely normal stock file and attitude. if it goes away after the write entire procedure then its either a corruption or a table somewhere was altered rendering a vss no show. when you select channels try choosing the generic option if a promt window asks you which signal to use.
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
    LNF-http://www.hptuners.com/forum/showth...357-LNF-Guides
    LSJ-http://www.hptuners.com/forum/showth...965-LSJ-Guides

  5. #5
    Haven't had a chance to flash as write entire. The vss not logging on the scanner has occurred since the first time I scanned the car. It was before I read and or wrote a calibration into them. Tried generic speed channels and the specific one off the ECU and TCM. You think it could be a bad vss sensor? That could be a reason for the trans not shifting at times.

  6. #6
    Senior Tuner cobaltssoverbooster's Avatar
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    when diagnosing stuff its always a possibility but there should be a channel regardless of sensor operation.
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
    LNF-http://www.hptuners.com/forum/showth...357-LNF-Guides
    LSJ-http://www.hptuners.com/forum/showth...965-LSJ-Guides

  7. #7
    The channels are there, I just do not get a reading whatsoever. Not even a 0. We got the stage 1 sensors to run more boost, car seems to be running fine now

  8. #8
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    Following ...Also Having issue with writing a good program file for the 5l40e......... I have had zero luck finding a local shop to tune it via Dyno...