Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1343

6E1–448

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Throttle Body Unit

The throttle body has a throttle plate to control the amount
of air delivered to the engine. The TP sensor and IAC
valve are also mounted on the throttle body.
Vacuum ports located behind the throttle plate provide the
vacuum signals needed by various components. Engine
coolant is directed through a coolant cavity in the throttle
body to warm the throttle valve and to prevent icing.

014RX040

GENERAL DESCRIPTION —
ELECTRONIC IGNITION SYSTEM

Camshaft Position (CMP)  Sensor

The camshaft position (CMP) sensor sends a  signal to
the PCM. The PCM uses this signal as a ”sync pulse” to
trigger the injectors in the proper sequence. The PCM
uses the CMP signal to indicate the position of the #1
piston during its power stroke. The CMP allows the PCM
to calculate true sequential fuel injection (SFI) mode of
operation. If the PCM detects an incorrect CMP signal
while the engine is running, DTC P0341 will set.
If the CMP signal is lost while the engine is running, the
fuel injection system will shift to a calculated sequential
fuel injection mode based on the last fuel injection pulse,
and the engine will continue to run. It will run in the
calculated sequential mode with a 1–in–4 chance of the
injector being correct.
For additional information, refer to DTC P0342.

014RX007

Crankshaft Position (CKP)  Sensor

The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position. For additional information, refer
to Electronic Ignition System.

Electronic Ignition

The electronic ignition system controls fuel combustion
by providing a spark to ignite the compressed air/fuel
mixture at the correct time. To provide optimum engine
performance, fuel economy, and control of exhaust
emissions, the PCM controls the spark advance of the
ignition system. Electronic ignition has the following
advantages over a mechanical distributor system:

D

No moving parts.

D

Less maintenance.

D

Remote mounting capability.

D

No mechanical load on the engine.

D

More coil cooldown time between firing events.

D

Elimination of mechanical timing adjustments.

D

Increased available ignition coil saturation time.

6E1–449

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

0013

Ignition Coils

The 2.2L engine uses 2 ignition coils, 1 per 2 cylinders. A
two–wire connector provides a 12–volt primary supply
through the 15–amp ignition coil fuse, and the ground wire
is connected to a ground–switching ignition module.
Radio frequency interference produced by the coil is
controlled by a condenser which is mounted near the
ignition coil.

014RX044

Ignition Control

The ignition control (IC) spark timing is the PCM’s method
of controlling the spark advance and the ignition dwell.
The IC spark advance and the ignition dwell are
calculated by the PCM using the following inputs:

D

Engine speed.

D

Crankshaft position (58X reference).

D

Camshaft position (CMP) sensor.

D

Engine coolant temperature (ECT) sensor.

D

Throttle position (TP) sensor.

D

Vehicle speed (vehicle speed sensor).

D

PCM and ignition system supply voltage.

Ignition Control Module (ICM)

The powertrain control module (PCM) controls engine
ignition through a solid–state switching unit called the
ignition control module (ICM). The software in the PCM
uses input from several sensors to determine the timing,
duration, and strength of the spark.

014RX042

D

The crankshaft position (CKP) sensor sends the PCM
a 58X signal related to the exact position of the
crankshaft.

0013

6E1–450

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

D

The camshaft position (CMP) sensor sends a signal
related to the position of the camshaft.

014RX007

Based on these sensor signals, as well as engine load
and engine coolant temperature information, the PCM
controls the switching function of the ICM by sending it a
5V signal. As long as the ICM receives the signal, it allows
battery voltage to the ignition coil. That voltage allows a
magnetic field to build in the coil.
When the PCM requires a spark plug to fire, it shuts off the
5V signal to the ICM grounding it internally. This triggers
the ICM to switch off the battery voltage to the ignition coil,
which causes the field to collapse. The lines of magnetic
force pass through the secondary portion of the coil as
they collapse. As they intersect the coil, they induce high
voltage in the secondary ignition circuit which travels
toward ground through the spark plug.

Ignition Control PCM Output

The PCM provides a zero volt (actually about 100 mV to
200 mV) or a 5–volt output signal to the ignition control
(IC) module. When the ignition control (IC) module
receives the 5–volt signal from the PCM, it provides a
ground path for the B+ supply to the primary side of the
coil and creates a magnetic field in the coil. When the
PCM shuts off the 5–volt signal to the ignition control
module, the ground path for the primary coil is broken.
The magnetic field collapses and induces a high voltage
secondary impulse which fires the spark plug and ignites
the air/fuel mixture.

Powertrain Control Module (PCM)

The PCM is responsible for maintaining proper spark and
fuel injection timing for all driving conditions. To provide
optimum driveability and emissions, the PCM monitors
the input signals from the following components in order
to calculate spark timing:

D

Engine coolant temperature (ECT) sensor.

D

Intake air temperature (IAT) sensor.

D

Throttle position (TP) sensor.

D

Vehicle speed sensor (VSS).

D

Crankshaft position (CKP) sensor.

Spark Plug

Although worn or dirty spark plugs may give satisfactory
operation at idling speed, they frequently fail at higher
engine speeds. Faulty spark plugs may cause poor fuel
economy, power loss, loss of speed, hard starting and
generally poor engine performance. Follow the
scheduled maintenance service recommendations to
ensure satisfactory spark plug performance. Refer to
Maintenance and Lubrication.
Normal spark plug operation will result in brown to
grayish–tan deposits appearing on the insulator portion of
the spark plug. A small amount of red–brown, yellow, and
white powdery material may also be present on the
insulator tip around the center electrode. These deposits
are normal combustion by–products of fuels and
lubricating oils with additives. Some electrode wear will
also occur.
Engines which are not running properly are often referred
to as ”misfiring.” This means the ignition spark is not
igniting the air/fuel mixture at the proper time. While other
ignition and fuel system causes must also be considered,
possible causes include ignition system conditions which
allow the spark voltage to reach ground in some other
manner than by jumping across the air gap at the tip of the
spark plug, leaving the air/fuel mixture unburned. Refer to
DTC P0300.
Misfiring may also occur when the tip of the spark plug
becomes overheated and ignites the mixture before the
spark jumps. This is referred to as ”pre–ignition.”
Spark plugs may also misfire due to fouling, excessive
gap, or a cracked or broken insulator. If misfiring occurs
before the recommended replacement interval, locate
and correct the cause.
Carbon fouling of the spark plug is indicated by dry, black
carbon (soot) deposits on the portion of the spark plug in
the cylinder. Excessive idling and slow speeds under light
engine loads can keep the spark plug temperatures so
low that these deposits are not burned off. Very rich fuel
mixtures or poor ignition system output may also be the
cause.Refer to DTC P0172.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear. This may be caused by
oil during break–in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the normal
red–brown, yellow or white deposits of combustion
by–products become sufficient to cause misfiring. In
some cases, these deposits may melt and form a shiny
glaze on the insulator around the center electrode. If the
fouling is found in only one or two cylinders, valve stem
clearances or intake valve seals may be allowing excess
lubricating oil to enter the cylinder, particularly if the
deposits are heavier on the side of the spark plug facing
the intake valve.

6E1–451

RODEO Y22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

TS23995

Excessive gap means that the air space between the
center and the side electrodes at the bottom of the spark
plug is too wide for consistent firing. This may be due to
improper gap adjustment or to excessive wear of the
electrode during use. A check of the gap size and
comparison to the gap specified for the vehicle in
Maintenance and Lubrication will tell if the gap is too wide.
A spark plug gap that is too small may cause an unstable
idle condition. Excessive gap wear can be an indication of
continuous operation at high speeds or with engine loads,
causing the spark to run too hot. Another possible cause
is an excessively lean fuel mixture.

TS23992

Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear. The plug and
the cylinder head seats must be in good contact for proper
heat transfer and spark plug cooling. Dirty or damaged
threads in the head or on the spark plug can keep it from
seating even though the proper torque is applied. Once
spark plugs are properly seated, tighten them to the
torque shown in the Specifications Table. Low torque may
result in poor contact of the seats due to a loose spark

plug. Overtightening may cause the spark plug shell to be
stretched and will result in poor contact between the
seats. In extreme cases, exhaust blow–by and damage
beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re–gapping, or heat shock to the insulator material. Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.

TS23994

A broken or cracked lower insulator tip (around the center
electrode) may result from damage during re–gapping or
from ”heat shock” (spark plug suddenly operating too
hot).

TS23993