ECU Controlled Combination Throttle Opener Dashpot

Dashpot and throttle opener functions are combined into one ECU controlled system on some late model engines like the '91 3E-E. This system uses an ECU controlled VSV to switch vacuum to the throttle opener/dashpot diaphragm.

• When the throttle angle closes beyond a specified point during deceleration, the ECU de-energizes the VSV, allowing manifold vacuum to bleed through the VTV and act on the diaphragm. This causes the control rod to gradually retract, slowly closing the throttle valve.

The idle air by-pass screw, dashpot, and throttle opener do not require routine adjustment. In the event that these components have been tampered with, refer to the appropriate repair manual for adjustment procedures of curb idle, dashpot, throttle opener, and A/C idle up.

Driving Mode


Port A

Port B (Bleed)

Port C

Acceleration and Cruise








• ECU turns VSV ON as throttle opens; rod extends

• ECU turns VSV OFF on deceleration; rod allows throttle to close slowly

• Engine OFF; rod extends, holding throttle open slightly

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