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Thread: Jet DST LT4 Vette Headers and Cold Air?

  1. #1
    Carb and Points!
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    Jet DST LT4 Vette Headers and Cold Air?

    Hi all I am new to the Forum and I have a newbee question!
    So I have an LT4 Vette with 1 3/4" ARH headers/cats, and Cold Air. I just bought a used JET DST and am familiar with tuning terms for the most part. I have already programmed my cooling fans to turn on faster and eliminated my CAGS (JET calls it CARS for whatever reason).
    My car runs great no issues but I am wondering if more HP could be gained by tuning the fuel and spark? If there is not much to be gained then I won't bother tuning as the car does run great.
    If there are decent gains by tuning then should I tune at an RPM level around 4000 RPM and up? I have a scan tool that will take readings and let me upload to my computer. I am thinking of making a few WOT runs to see what it looks like and then start adjusting but I am new to this so any suggestions would be appreciated

  2. #2
    Carb and Points!
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    What is CAGS/CARS? I also just started using DST and trying to learn the terms. Thx

  3. #3
    Carb and Points!
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    Quote Originally Posted by TonyT1996 View Post
    What is CAGS/CARS? I also just started using DST and trying to learn the terms. Thx
    CAGS is Computer Aided Gear Selecton (it is when you are driving slow and the computer engages a solenoid inside the manual transmission to force a 1st to 4th shift). JET DST calls this CARS and I have no idea why, I think they misspelled CAGS.
    Good luck with your tuning there is certainly not much out there for help on the LT4 engines. I stopped playing after turning off the CAGS, lowering my electric fan turn on temperature and giving a slight timing boost in the upper RPMs.
    The car doesn't ping and runs great but it is trial and error and I was extremely conservative with my adjustment (probably no gain at all for horsepower but the engine runs nicely).
    Last edited by grandspt; 03-30-2017 at 04:25 PM.

  4. #4
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    CARS = Computer Aided Ratio Selection. Engineering term.
    CAGS = Computer Aided Gear Selection. Marketing term.

  5. #5
    Carb and Points!
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    Quote Originally Posted by 1project2many View Post
    CARS = Computer Aided Ratio Selection. Engineering term.
    CAGS = Computer Aided Gear Selection. Marketing term.
    So DST considers the skip shift a gear ratio selection hence CARS. Makes sense but it would have been easier for me if they called it CAGS. :-) It took me a while to figure out that CARS would disable the skip shift.

  6. #6
    Carb and Points!
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    So I appreciate the dictionary meaning of the CARS do you have any tuning tips?
    Last edited by grandspt; 03-30-2017 at 04:30 PM.

  7. #7
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    Last time I tuned an LT4 was in... umm... 2001 or 2002? Step 1 was to remove Hypertech tuning. After that I worked on reducing delivered fuel at WOT. That helped improve power level but I had a chassis dyno available so I could make changes in increments. The next step would have been looking at the WOT enable parameters to see if they seemed appropriate for the owner's style of driving. I seem to remember that I liked much of the LT4 tune as was and without having time to do some on-street driving I wasn't going to make too many changes.

  8. #8
    Fuel Injected!
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    Id love to get a genuine LT4 stock file. You know, for safe keeping of course.

    Chris

  9. #9
    Fuel Injected!
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    Edit: After looking further into JET DST I realize i had it confused with a hypertech style programmer. I see now that it is a complete suite and looks fully capable. So disregard some of my post in regards to the JET DST. The OBD2 LT1/4 kind of got the short end of the stick when it came to tuning. It seems most people with LT1s tune on OBD1. The OBD1 LT1s continue to be disassembled, over the last few years there have been several new tables discovered and added to the xdf. Also people have continued to develop patches that allow for new functionality that was never originally there.

    ---------------------------------------------------------------------------------------------------------------------------


    if you guys are talking about the LT4 and not the LT5 (ZR1), tuning the LT4 should be no different then tuning an LT1.

    The one size fits all tuners i.e. JET DST, Hypertech, etc. are great if all you want to do is lower fan temps and disable CAGS or other simple on/off items. other than that they are absolute garbage compared to whats available. not to mention more expensive.

    If your corvette is a '96, I would suggest looking at reverting it to OBD1 from OBD2.

    There is amazing software available for the OBD1 LT1s. EEhack is completely free and blows most tuning software out of the water.
    combine that with TunerPro, which is also free, and you now have complete tuning capability minus a dyno. the only equipment you'd need to purchase is an ALDL-to-USB cable from moates.com or other cable vendor.
    Last edited by johnny_b; 11-06-2017 at 11:02 PM.

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