Merkur Xr4ti L4-140 2.3L SOHC Turbo (1985)
FIGURE 1 - TURBOCHARGER BOOST CONTROL SYSTEM LAYOUT
VEHICLE APPLICATION
Thunderbird Merkur/XR4Ti
DESCRIPTION
The turbocharger boost control system is designed to provide electronic variable boost control on the 2.3L electronic fuel injected turbocharged engine.
The boost control system provides regulation of the wastegate actuator signal allowing turbo boost pressures up to 89.6-110.3 kPa (13.0-16.0 psi) on
manual transmission vehicles and 55.1-75.8 kPa (8.0-11.0 psi) on automatic transmission vehicles. The system includes a control module, solenoid/hose
assembly, calibrated "T" fitting and all controlled by the EEC module (Fig. 1). The boost control system is activated in the PREMIUM fuel selection
position only, on manual transmissions. On automatic transmissions, it is activated in both the REGULAR and PREMIUM positions. See Note (A).
OPERATION
Refer to Fig. 1.
On vehicles equipped with manual transmissions, with the fuel selector switch in REGULAR position, boost pressure is limited by the wastegate to
approximately 69 kPa (10 psi). When boost pressure reaches 69 kPa (10 psi), the wastegate is opened, bypassing exhaust gases away from the turbine
blades, limiting turbo boost pressure.
When the fuel selector switch is in the PREMIUM position, the EEC module sends open and close commands to the turbo boost control module which,
in turn, energizes or de-energizes the solenoid. When the solenoid is energized, a portion of the pressure signal to the wastegate actuator is diverted to
the inlet side of the boost solenoid. This will result with higher boost pressures 89.6-110.3 kPa (13-16 psi) maximum. Boost pressure varies between
68.95 and 110.3 kPa (10 and 16 psi) depending on rpm, vehicle, speed and transmission gear selection. See Note (B).
On vehicles equipped with automatic transmissions, the boost control solenoid operation is identical with the fuel selector switch in either REGULAR or
PREMIUM position. Solenoid operation is similar to the operation described earlier for PREMIUM position on vehicles equipped with manual
transmissions, except boost pressures are lower 55.1-75.8 kPa (8-11 psi) maximum. Boost pressure varies between 41.3-75.8 kPa (6-11 psi) depending
on RPM and vehicle speed. See Note (B).
NOTES:
(A)
Merkur/XR4Ti does not have an Octane Switch. Boost control is activated at all times on automatic and manual transmission.
(B)
Merkurs with manual or automatic transmissions operate the same as Turbo-Thunderbirds with the Octane Switch in the premium position.
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Turbocharger Boost Control System
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