1993 CHEVROLET PLYMOUTH ACCLAIM Service Manual

keyless entry hood release maintenance schedule navigation update parking sensors fuel tank removal

Page 1833 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual CRUISE OR IDLE MODE
When the engine is at operating temperature, this is
a CLOSED LOOP mode. During cruising speed the
following inputs are received by the PCM:
² engine coolant temperature
² kn

CRUISE OR IDLE MODE
When the engine is at operating temperature, this is
a CLOSED LOOP mode. During cruising speed the
following inputs are received by the PCM:
² engine coolant temperature
² knock sensor
² manifold absolute pressure
² engine speed (crankshaft position sensor)
² throttle position
² exhaust gas oxygen content
² A/C control positions
² battery voltage
The PCM provides a ground path for the injectors to
precisely control injector pulse width. The PCM adjusts
engine idle speed and ignition timing. The PCM con-
trols the air/fuel ratio according to the oxygen content
in the exhaust gas.
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recognizes
an abrupt increase in throttle position or MAP pres-
sure as a demand for increased engine output and
vehicle acceleration. The PCM increases injector pulse
width in response to increased fuel demand.
DECELERATION MODE
This is a CLOSED LOOP mode. During deceleration
the following inputs are received by the PCM:
² engine coolant temperature
² knock sensor
² manifold absolute pressure
² engine speed (crankshaft position sensor)
² throttle position
² exhaust gas oxygen content ²
A/C control positions
² battery voltage
The PCM may receive a closed throttle input from
the throttle position sensor (TPS) at the same time it
senses an abrupt decrease in manifold pressure. This
indicates a hard deceleration. The PCM modifies the
injector sequence. This helps maintain better control
of the air-fuel mixture.
WIDE OPEN THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are received
by the PCM:
² engine coolant temperature
² knock sensor
² manifold absolute pressure
² engine speed (crankshaft position sensor)
² throttle position
When the PCM senses a wide open throttle condi-
tion it will de-energize the air conditioning relay.
This disables the air conditioning system. The exhaust gas oxygen content input is not ac-
cepted by the PCM during wide open throttle opera-
tion. The PCM will enrichen the air/fuel ratio to
increase performance and compensate for increased
combustion chamber temperature.
IGNITION SWITCH OFF MODE
This is an OPEN LOOP mode. When the ignition
switch is turned to the OFF position, the following
occurs:
² All outputs are turned off.
² No inputs are monitored.
² The PCM shuts down.
Fig. 20 Throttle Body
Ä FUEL SYSTEMS 14 - 93

Page 1834 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual THROTTLE BODY
The throttle body assembly is located on the left
end of the intake manifold plenum (Fig. 20). The
throttle body houses the throttle position sensor and
the idle air control motor. Air

Page 1835 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual 2.2L TURBO III MULTI-PORT FUEL INJECTIONÐGENERAL DIAGNOSIS INDEX
page page
Fuel System Diagram ..................... 95 Visual Inspection......................... 95
FUEL SYSTEM DIAGRAM
Refer to th

Page 1836 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual (4) Verify the harness connector is attached to the
MAP sensor (Fig. 4).
(5) Check vacuum hose connections between vac-
uum source and canister purge, wastegate, and baro-
metric read solenoids (Fi

Page 1837 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual (15) Inspect the engine and fuel injector harness to
main harness electrical connections. (16) Verify that all electrical connectors are fully
inserted into relays and that battery connections are

Page 1838 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual (24) Inspect fuel injectors wiring connectors (Fig.
15). (25) Inspect the knock sensor electrical connector
(Fig. 16). (26) Inspect the heated oxygen sensor electrical con-
nector (Fig. 17). (27) Ver

Page 1839 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual (31) Check hose and wiring connections at fuel
pump. Check that wiring connector is making con-
tact with terminals on pump.
Fig. 18 Hose Connections
Fig. 19 Vehicle Speed Sensor Wiring Connector
Ä

Page 1840 of 2438

CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual 2.2L TURBO III MULTI-PORT FUEL INJECTIONÐON-BOARD DIAGNOSTICS INDEX
page page
60-Way PCM Wiring Connector ............. 105
Circuit Actuation Test Mode ................ 105
Diagnostic Trouble Co

2.2L TURBO III MULTI-PORT FUEL INJECTIONÐON-BOARD DIAGNOSTICS INDEX
page page
60-Way PCM Wiring Connector ............. 105
Circuit Actuation Test Mode ................ 105
Diagnostic Trouble Code Description ......... 101
General Information ...................... 100
High and Low Limits ..................... 101
Ignition Timing Procedure ................. 105 Monitored Circuits
....................... 100
Non-Monitored Circuits ................... 100
State Display Test Mode .................. 104
System Tests .......................... 104
Throttle Body Minimum Air Flow Check Procedure ............................ 105
GENERAL INFORMATION
The powertrain control module (PCM) has been pro-
grammed to monitor many different circuits of the fuel
injection system. If a problem is sensed with a moni-
tored circuit often enough to indicate an actual prob-
lem, the PCM stores a fault. If the problem is repaired
or ceases to exist, the PCM cancels the Diagnostic
trouble code after 51 vehicle key on/off cycles. Certain criteria must be met for a diagnostic trouble
code to be entered into PCM memory. The criteria may
be a specific range of engine RPM, engine temperature,
and/or input voltage to the PCM. It is possible that a diagnostic trouble code for a
monitored circuit may not be entered into memory
even though a malfunction has occurred. This may
happen because one of the diagnostic trouble code
criteria for the circuit has not been met. For example,
assume that one of the diagnostic trouble code criteria
for a certain sensor circuit is that the engine must be
operating between 750 and 2000 RPM. If the sensor
output circuit shorts to ground when engine RPM is
above 2400 RPM (resulting i n a 0 volt input to the
PCM) a diagnostic trouble code will not be entered into
memory. This is because the condition does not occur
within the specified RPM range. There are several operating conditions for which the
PCM does not monitor and set diagnostic trouble codes.
Refer to Monitored Circuits and Non-Monitored Cir-
cuits in this section. Stored diagnostic trouble codes can be displayed
either by cycling the ignition key On - Off - On - Off -
On, or through use of the DRB II scan tool. The DRBII
scan tool connects to the data link connector in the
vehicle (Fig. 1).
MONITORED CIRCUITS
The powertrain control module (PCM) can detect
certain fault conditions in the fuel injection system. Open or Shorted Circuit - The PCM can determine
if the sensor output (input to PCM) is within proper
range. Also, the PCM can determine if the circuit is
open or shorted. Output Device Current Flow - The PCM senses
whether the output devices are hooked up. If there is a problem with the circuit, the PCM senses whether
the circuit is open, shorted to ground, or shorted
high. Oxygen Sensor - The PCM can determine if the
oxygen sensor is switching between rich and lean
once the system has entered closed loop. Refer to
Modes of Operation in this section for an explanation
of closed loop operation.
NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems and conditions that could have malfunctions
that result in driveability problems. Diagnostic trou-
ble codes may not be displayed for these conditions.
However, problems with these systems may cause di-
agnostic trouble codes to be displayed for other sys-
tems. For example, a fuel pressure problem will not
register a fault directly, but could cause a rich or
lean condition. This could cause an oxygen sensor
fault to be stored in the PCM. Fuel Pressure - Fuel pressure is controlled by the
fuel pressure regulator. The PCM cannot detect a
clogged fuel pump inlet strainer, clogged in-line fuel
filter, or a pinched fuel supply or return line. How-
ever, these could result in a rich or lean condition
causing an oxygen sensor fault to be stored in the
PCM.
Fig. 1 Data Link Connector LocationÐAG Body
14 - 100 FUEL SYSTEMS Ä

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