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Thread: 12592525 LS9 MAP. Can't request more than 23.8 psi.

  1. #1

    Default 12592525 LS9 MAP. Can't request more than 23.8 psi.

    Like the title state's I can't get Holley boost control request to be more than 23.8 psi. I can move the table to be higher, but the logged request will not go higher. It is the last version of V4. I'm using the MAP configuration from the drop down menu. Is there some limit that I"m missing? I figured the 3 bar MAP sensor should be good to just over 29 psi. And no I'm not at some crazy baro. It's around 100 kPa baro right now. Got a big race coming up and I might need a little more.

  2. #2
    Join Date
    Dec 2009


    I'm on V4 EFI software too, and Holley's 3 bar MAP sensor axis programs to 31.2 PSIG. (I don't know why yours is limited to 23.8 PSIG.)
    Just for reference: (MAP kPa to Boost PSI Equivalents & Boost Control Information)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3


    I have proved the MAP sensor could see the output. I put a 25.5 psi spring in the wastegate, but I have not resolved the original problem and have discovered a few more. I'm wondering why my wastegate duty cycle datalogs show -100%. I was able to get decent boost control with a single solenoid setup just running 23.8 psi boost on a 18 psi spring on the dyno, but it would run at 18 psi on the track with -100% DC. It could just be a back pressure issue, but it seems odd that the precision spring chart was so close to accurate.
    Attachment 3495

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