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  1. #1
    Junior Member PHLTHS's Avatar
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    Dec 2014
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    Post 4L60E Shift Pressure Knowledge

    Hi All,

    I just would like some clarification about the 4L60E experts here on the forum.

    From what I can tell, the pump in the auto picks up the fluid and pumps it towards the PRESSURE REG VALVE / BOOST VALVE located in the pump assembly itself.

    This is LINE PRESSURE that is coming from the pump, when in drive ranges from Min: 55-65psi to Max:170-190psi from factory. How pressure is blead off is determined by the "TORQUE SIGNAL" as I think the clutch packs do not require this full force?

    This "TORQUE SIGNAL" is recieved from the EPC / PCS (PRESSURE CONTROL SOLENOID VALVE). This is a table that is applying a current in mA which alters the PRESSURE REG VALVE / BOOST VALVE bleed off point. This can be alterated / scaled using the Force Motor Current table D3801 to either increase / decrease the overall pressure for the entire system including TCC's fluid pressure. I've also seen some people turn the screw at the back of the EPC / PCS Valve either 1/8 to 1/4 of a turn clockwise to change the base setpoint.

    When using the MAF a per normal on the LS1's there Torque Signal Pressure is scaled correctly. It ranges from 0-96PSI Torque Signal Pressure. Just like with E38's when running SD if the airflow table isn't corrected so that the correct Delivered Engine Torque is correct the Auto might not apply the correct line pressure as required.

    I guess then the only question I have about the Auto's is this:

    D3801 Force Motor Current controls the overall pressure for the transmission.

    D0701 Base Pressure 1>2 Shift
    D0702 Base Pressure 2>3 Shift
    D0703 Base Pressure 3>4 Shift

    So, are tables are basically altering the pressure applied for the actual shift itself just to complete the shift? So more pressure = firmer shift / less pressure = softer shift.

    But once applied, the claming force to keep the clutch packs locked up is based on D3801 bascially? or is it based on either of the D0701 - D0703 tables to determe each gears clamping force?

    I'm in the middle of building a 4L60E using the Sonnax HP-4L60E-01 Performance Shift Pack and I'm worried that not having this tuned correctly will allow the clutch packs to slip with boosted power etc.


    Thank you.
    Last edited by PHLTHS; March 8th, 2020 at 11:57 PM.
    HSV W427 / HSV SportsCat SV

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