Chrysler PT Cruiser 2001 Service Manual Supplement page 2465

The PCM determines the spark advance based on
the following:
– engine coolant temperature
– crankshaft position
– intake air temperature
– manifold absolute pressure
– throttle position
Engine Warm-Up Mode - This is an open loop
mode. The PCM adjusts injector pulse width and
controls injector synchronization by controlling the
fuel injectors' ground paths. The PCM adjusts igni-
tion timing and engine idle speed. The PCM adjusts
the idle speed by controlling the idle air control
motor and spark advance.
Cruise or Idle Mode - When the engine is at
normal operating temperature, this is a closed loop
mode.
Acceleration Mode - This is a closed loop mode.
The PCM recognizes an increase in throttle position
and a decrease in manifold vacuum as engine load
increases. In response, the PCM increases the in-
jector pulse width to meet the increased load. The
A/C compressor may be de-energized for a short
period of time.
Deceleration Mode - This is a closed loop mode.
The PCM recognizes a decrease in throttle position
and an increase in manifold vacuum as engine load
decreases. In response, the PCM decreases the
injector pulse width to meet the decreased load.
Full injector shut off may be obtained during high
speed deceleration.
Wide Open Throttle Mode - This is an open
loop mode. The throttle position sensor notifies the
PCM of a wide open throttle condition. Once a wide
open throttle is sensed, the PCM de-energizes the
A/C compressor clutch relay for 20 seconds.
3.2.5 NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems, and conditions even though they could
have malfunctions that result in driveability prob-
lems. A diagnostic code may not be displayed for the
following conditions. However, problems with these
systems may cause a diagnostic code to be displayed
for other systems. For example, a fuel pressure
problem will not register a diagnostic code directly,
but could cause a rich or lean condition. This could
cause an oxygen sensor, fuel system, or misfire
monitor trouble code to be stored in the PCM.
Engine Timing - The PCM cannot detect an
incorrectly indexed
sprocket, or crankshaft sprocket. The PCM also
cannot detect an incorrectly indexed distributor.(*)
Fuel Pressure - Fuel pressure is controlled by
the fuel pressure regulator. The PCM cannot detect
timing chain, camshaft
GENERAL INFORMATION
a clogged fuel pump inlet filter, clogged in-line filter,
or a pinched fuel supply.(*)
Fuel Injectors - The PCM cannot detect if a fuel
injector is clogged, the pintle is sticking, or the
wrong injectors are installed.(*)
Fuel Requirements - Poor quality gasoline can
cause problems such as hard starting, stalling, and
stumble. Use of methanol-gasoline blends may re-
sult in starting and driveability problems. (See
individual symptoms and their definitions in Sec-
tion 6.0 (Glossary of Terms).
PCM Grounds - The PCM cannot detect a poor
system ground. However, a diagnostic trouble code
may be stored in the PCM as a result of this
condition.
Throttle Body Air Flow - The PCM cannot
detect a clogged or restricted air cleaner inlet or
filter element.(*)
Exhaust System - The PCM cannot detect a
plugged, restricted, or leaking exhaust system.(*)
Cylinder Compression - The PCM cannot de-
tect uneven, low, or high engine cylinder compres-
sion.(*)
Excessive Oil Consumption - Although the
PCM monitors the exhaust stream oxygen content
through the oxygen sensor when the system is in a
closed loop, it cannot determine excessive oil con-
sumption.
(*)NOTE: ANY OF
COULD RESULT IN A RICH OR LEAN
CONDITION CAUSING AN OXYGEN SENSOR
TROUBLE CODE TO BE STORED IN THE
PCM, OR THE VEHICLE MAY EXHIBIT ONE
OR MORE OF
SYMPTOMS LISTED IN The TABLE OF
CONTENTS.
3.2.6 SKIS OVERVIEW
The Sentry Key Immobilizer System (SKIS) is an
immobilizer system designed to prevent unautho-
rized vehicle operation. The system consists of a
Sentry Key Immobilizer Module (SKIM), ignition
key(s) equipped with a transponder chip and engine
controller. When the ignition switch is turned on,
the SKIM interrogates the ignition key. If the igni-
tion key is Valid the SKIM sends a PCI Bus mes-
sage to the engine controller indicating the pres-
ence of a valid ignition key. Upon receiving a Valid
key signal the PCM allows the engine to continue to
operate.
3.2.7 SKIM ON-BOARD DIAGNOSTICS
The SKIM has been programmed to transmit and
monitor many different coded messages as well as
PCI Bus messages. This monitoring is called On-
Board Diagnosis.
5
THESE CONDITIONS
THE DRIVEABILITY