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Thread: VVE only e38 single plane intake (SWAP) Fuel Cut?Airflow Limit? Have logs and files!

  1. #1

    VVE only e38 single plane intake (SWAP) Fuel Cut?Airflow Limit? Have logs and files!

    Good morning everyone! I don't post too often because I can usually search and find what Im looking for but this one has me stumped! A client brought me a 2nd gen TA with a single plane intake on a built LS3. It had a corvette OS and during tuning, on startup, it would go into RAP. I found out he was using an 87mm truck TB to make the shaker hood fit and the throttle stops must be different between the LS3 tb and truck causing RAP. So I changed to a 2012 Silverado OS that used the same TB and the issue was solved. However now I'm left with a new issue where the car seems to go into reduced power past a certain throttle angle or amount of airflow. I have tested with a known good tb and it did not change anything. I noticed in the earlier logs where it was lean I could go full wot without it going into reduced power but after adding fuel to the ve map in the wot areas it began going into reduced power.

    I brought all my idle and other data from the vette tune but kept the truck tb settings. The cars starts, idles, and drives very well all the way to about 60% throttle at which point it shoots lean then goes into what appears to be RAP (throttle is dead) with no dtc other than sometimes Ive seen a p0606? A battery disconnect or clicking clear dtc's in the scanner brings it back to normal. Ive logged air, fuel and spark torque management source pids during the events and all read NONE. I believe I have done the RPM zones correctly but this is the first time Ive tried running VVE to redline so maybe Ive done something wrong. I can see in the logs where the delivered torque will shoot down if I irritate it some but not enough to go dead. Id appreciate any info or help you can give. Ive had to send the car home but will have it back in a week or so to do more diagnostics.
    Last edited by topher455; 2 Weeks Ago at 11:31 AM.
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  2. #2
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    What tool did you use to change the OS?

  3. #3
    Advanced Tuner jsllc's Avatar
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    Can you post the original tune in the car before your swap?
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  4. #4
    Good morning! Thanks to both of you for the reply. I changed the OS by doing a write entire with the hpt interface. The original file in the new pcm is the first tune file I posted. I found a list that showed compatibility between the two OS over on the "other" site before writing it. Revision 13 is where I first rolled into it and saw it go lean up top. The car leaned out to 15-16 afr from 12.5 in a split second and laid down but never went into rap. Revision 14 I added about 20% fuel above about 85 kpa then the car would still lean out the same way then go into rap requiring me to clear all dtc's or disco the battery.
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  5. #5
    I realized you may want something else to compare with so here are two other files. The first is the truck os I used to upload with the new pcm. Its a friends truck so I know it well and can get access to it if I needed it so I figured it was a good choice. Ill also include the base tune file I had built for the 09 Vette OS before I found out about the TB.

    12 Silverado 5.3 6l80e lifted 6 on 35 stock file.hpt

    71 Trans Am ls3 4l80e tuned rev3 vve adjusted.hpt
    Last edited by topher455; 2 Weeks Ago at 09:12 AM.
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  6. #6
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    Quote Originally Posted by topher455 View Post
    I changed the OS by doing a write entire with the hpt interface.
    That doesn't work when changing between OSes that have incompatible TACs. Try it again using the same current Silverado VIN, but this time using Tech2/MDI. Copy over changes afterward. Your leaning out is the result of hitting REP (because of the leftover Vette TAC code left behind in the truck OS), not the cause.

  7. #7
    Advanced Tuner jsllc's Avatar
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    Actually, I believe you have other issues as well. From what you posted you took a first gen e38 with an OS that was never designed to support over 65 lb/hr injector data and flashed an os that supports 127 lb/hr injectors. If that really worked every older vet owner in the world would be doing it. It is my understanding at the hardware level they fundamentally different. So no a good idea. ECM really needs to go back to stock using Tech2/MDI and the issue fixed there. Whatever the issue it can be fixed.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  8. #8
    That makes sense about the tac programming. I will try having it programmed stock to that OS I used then write in the calibration afterwards. Thank you!

    As far as the swapping OS part, I may not have been clear. The car came to me with an 09 Vette OS I initially attempted to write an 09 Escalade OS to that pcm to make use of the truck TB. The PCM bricked after the OS swap. Supposedly the two OS were compatible but apparently not. I did read that swapping OS on 08-10 was kind of dicey.. So when we got a new computer I chose to use a 12 OS instead since it was widely compatible and ordered the PCM based off the vin of the truck I planned to use. So the original file that came in the new pcm is the "full read after new pcm" I have attached above. Then I swapped it to the 12 truck OS so there shouldn't be any incompatibilities unless you are looking at the original vette file and the current truck one.

    Thank you both for taking the time to reply and look at this with me!!!
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  9. #9
    I have an appointment set up to take the car into the dealer that I know well so we can write the OS to the car fully. I didn't realize that the write entire process was different than having the file uploaded with the GM tool. I was wondering, what are the limitations of the write entire process? Ive used it on new TECHM assemblies before without any apparent issues. Should I have had them written at the dealer?
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  10. #10
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    GM ECM files from GM TIS and written with a Tech2/MDI have 8 segments:
    Main Operating System
    System
    Fuel System
    Speedometer
    Engine Diagnostic
    Engine Operation
    Slave Operating System
    Engine

    GM ECM files in HPTuners have only 6 segments:
    Main Operating System
    System
    Fuel System
    Speedometer
    Engine Diagnostic
    Engine Operation

    The ETC controller is run by Slave Operating System & Engine (one or both, we can't look inside to see what's what), segments which aren't present in the HPT files. Doing a 'write entire' will leave those two untouched. So if they were the wrong ones before, they'll still be the wrong ones afterward.

    Attached Images Attached Images

  11. #11
    I see! Excellent explanation. Thanks very much!
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