Ciera Cruiser V6-173 2.8L VIN W FI (1986)
Idle Speed/Throttle Actuator - Electronic: Technical Service Bulletins
Idle Speed Actuator - Circuit Operation
SUBJECT
IDLE SPEED ACTUATOR (THROTTLE KICKER)
CIRCUIT OPERATION ON 2.8L V-6 (VIN CODE X) ENGINE
MODELS/YEARS 1986 CUTLASS CIERA/CUTLASS CRUISER
NUMBER:
86-T-71
CORP.REF.NO.: 616515R
DATE:
April 1988
SECTION:
6E
Chart C-2E-1 on page 6E1-C2-12 and 6E1-C2-13 in Volume I and the "A" car electrical schematic on page 63-7 in Section 8A in Volume 11 of the 1986
Firenza, Calais, Cutlass Ciera, Delta 88 and Ninety-Eight Chassis Service Manual have been revised.
Please update the above pages in your respective service manuals with the revised information in this bulletin.
1.
Circuit Operation-General Description
The E2SE carburetors use a Vacuum Operated Idle Speed Actuator (throttle kicker) that is mounted on the carburetor. The idle speed actuator
plunger is normally retracted (throttle not held open by plunger). Vacuum to the idle speed actuator is controlled by an idle speed actuator vacuum
solenoid. The vacuum solenoid is energized two ways:
1.
ECM control - energizes vacuum solenoid:
a.
When engine coolant is below 85~C (185~F)
b.
For 30 seconds after every engine start up, if coolant is above 85~C (185~F).
c.
On engine deceleration, using a calibrated TPS and RPM value to allow a greater throttle opening for improved emissions
2.
Vacuum solenoid relay control - energizes vacuum solenoid:
a.
When A/C control head is in MAX, NORM, BI-LEVEL, or DEF position, if A/C pressure cycling switch is closed
b.
Power steering cut out switch is open (high P/S line pressure)
The vacuum solenoid is normally open (no vacuum through to idle speed actuator) and the vacuum solenoid relay is normally closed.
II. Circuit Operation - Theory
The Idle Speed Actuator (throttle kicker) is used to control idle speed as commanded by the ECM and/or vacuum solenoid relay (throttle kicker
relay).
Inputs to the ECM are distributor reference, TPS, RPM, and coolant temperature. Inputs to the vacuum solenoid relay are A/C on signal and the
power steering cut out switch status.
The ECM and/or vacuum solenoid relay control the vacuum solenoid valve and the vacuum solenoid valve controls the idle speed actuator, which
controls idle speed.
When the engine is started, the ECM grounds the vacuum solenoid causing the solenoid valve to close (vacuum panes through to idle speed
actuator) thereby causing the idle speed actuator to extend and increase idle speed. The ECM keeps the vacuum solenoid grounded (closed) for 30
seconds after the first distributor reference pulse is received or until the coolant temperature reaches 85~C (185~F), whichever occurs last. The
ECM will also ground the vacuum solenoid during engine deceleration, using a calibrated TPS and RPM value, to allow a greater throttle opening
for improved emissions.
Independent of ECM control over the idle speed actuator and vacuum solenoid is the vacuum solenoid relay. The vacuum solenoid relay energizes
the idle speed actuator and vacuum solenoid by providing an auxiliary ground path for the vacuum solenoid. The vacuum solenoid relay
de-energizes the idle speed actuator and vacuum solenoid by opening and interrupting the ground circuit for the vacuum solenoid (assuming the
ECM is not grounding the vacuum solenoid).
The vacuum solenoid relay is normally closed, de-energized, and opens when energized. The vacuum solenoid relay may be de-energized when the
ignition is on by:
1.
Turning A/C control to MAX, NORM, BI LEVEL or DEF position (A/C pressuring cycling switch closed). This allows system voltage to
both sides of the relay coil.
