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Thread: 1998 Trans Am LS7 with Procharger 10 to 11 PSI peak. Thoughts about some fine-tuning

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    Default 1998 Trans Am LS7 with Procharger 10 to 11 PSI peak. Thoughts about some fine-tuning

    First time I've been able to tune consistently because it broke every 4L60E or build I put in. Now that the 4L80E is living, I got some hurdles.

    1. I got some LTFT's going into WOT
    2. Tip into boost always hits lean for a moment
    3. 50 to 60% throttle (close to boost) was rich 10:1... I began to get away from that, but still struggling
    4. I usually have KR in 1st gear, but barely any when rolling and hit from 2nd gear.
    5. I finally got more consistent mid 11's for AFR. It seems to like mid to upper 11's.
    6. I change from dual Walbros to single Hellcat and upgraded Boost referenced FPR with bigger bowl and 8AN return.. and 8AN Rails

    Any advice would be appreciated. Here is some data.

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    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

  2. #2
    Joe (Moderator) joecar's Avatar
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    Post IFR, VE and PE tables.


    ( or post your tune file file and some log files )

  3. #3
    Joe (Moderator) joecar's Avatar
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    Which desert are you in?

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    Quote Originally Posted by joecar View Post
    Post IFR, VE, and PE tables.
    ( or post your tune file file and some log files )
    LS1B_0796_240207_VE_VBE_Mechanical Blvd.efi

    240207_VE_VBE.ctz

    This is the one where I basically spun through 1st, 2nd, and most of 3rd before backing out of WOT. (ctz and efi files)

    There is plenty of driving data in the log file
    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

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    Quote Originally Posted by joecar View Post
    Which desert are you in?
    LOL... the desert is composited background behind my car.

    Click image for larger version. 

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    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

  6. #6
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    Walkaround video of it idling
    https://youtu.be/GRehF-VDyuM
    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

  7. #7
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    I described to the guy at the performance shop.

    1. Initial startup perfect, settles down into good P/N idle and chops nicely when I put it in gear.
    1a. When I touch the throttle, it loses that stability and surges at idle where I have to back out the garage with my foot lightly on the pedal to avoid cutting off.

    2. When I get to a stop sign or light, I have to put foot on the pedal to avoid it dropping below target idle and cutting off.
    2a. If, while at light, I put it in Park or Neutral, it will idle, settle out, and I can immediately put it in gear, and it chops at 800 RPMs like a champ.
    2b. After that little cycle ins step 2a, at remaining stops, it idles just fine without cutting off.

    3. If I park the car and come back out the store and start up again, many times it will rev about 2200 RPMs and hang there a few seconds, so I pat the accelerator to settle it out. It then surges up and down in P/N and in gear. I have to drive it a ways, and when I stop, I can cycle back through Step 2a successfully.

    Just weird, to me.

    I didn't really have this problem with the 92mm TB and I am having trouble dialing this 102mm in.

    I have the 102mm on because I bought when I tried running an LSXr Intake (bought used). This was the problem I was having and I thought it was the intake... it just wasn't worth the drivability issue and I couldn't get the idle settled out, so I put the LS7 intake back on.

    I have sprayed around the engine compartment and no change in idle tone. I bought a smoke tester and put that on, and there are no visible leaks.
    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

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    I have P305/R19/35 Mickey Thompson ET Street S/S on the rear.

    I know there is not a lot of WOT data. To really move forward, as if racing on the street, I can only give it about 3/4 throttle.
    When I WOT, it spins as long as I hold the pedal down, even when I feather it. (I guess that's a good problem to have, in a way).

    I am going to put a methanol kit in and then go to the Dyno, then to the track so that I can get some hookup and real data.

    I'm running Race Gas Additive right now to avoid all but some spurious KR.
    I'd rather be blown, bored... AND stroked!
    Now: 447 CID (Corvette 427) , ATI Procharger D-1SC Supercharger

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