IGNITION TIMING
IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM) TABLE\
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Application ( 1) Basic ( 2) ( 3) ( 4) Actual
1.5L ................ 2-8 @ 650-750 ....... 10 @ 600-800
1.8L ................ 2-8 @ 600-800 ........ 5 @ 600-800
2.0L
Non-Turbo .............. ( 5) ..................... ( 5)
Turbo ............. 2-8 @ 650-850 ........ 8 @ 650-850
2.4L ................ 2-8 @ 650-850 ....... 10 @ 650-850
3.0L ................ 2-8 @ 600-800 ....... 15 @ 600-800
3.5L ................ 2-8 @ 600-800 ....... 15 @ 600-800
( 1) - With ignition timing adjustment connector grounded or
vacuum hose (farthest from distributor) disconnected.
( 2) - With ignition timing adjustment connector ungrounded
or vacuum hose (farthest from distributor) connected.
( 3) - If vehicle altitude is more than 2300 feet above sea
level, actualtiming may be advanced (5 degrees).
( 4) - Actual ignition timing is approximate and may
fluctuate plus or minus 7 degrees.
( 5) - Ignition timing is NOT adjustable.
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Fig. 2: Locating Data Link Connector (Typical)
Courtesy of Mitsubishi Motor Sales of America
3000GT (DOHC)
1) Ignition timing is controlled by Powertrain Control Module
(PCM) and is not adjustable. Manufacturer provides procedure for
checking timing.
2) Start engine and warm engine until engine temperature
is 600-700 RPM. Turn engine off. Curb idle speed is automatically
controlled by Idle Air Control (IAC) system. If curb idle speed is not\
as specified, see DTC P0505 in G - TESTS W/CODES article.
4) Disconnect waterproof female connector from Brown ignition
timing check connector. See Fig. 4. Using a jumper wire, ground
ignition timing check terminal to read basic ignition timing. Using
timing light, read basic ignition timing value. See
IGNITION TIMING SPECIFICATIONS table. If basic ignition timing is
within specification, go to next step. If basic ignition timing is not
within specification, see DTC P0335 in G - TESTS W/CODES article.
5) Remove jumper wire to read actual ignition timing. Using
timing light, read actual ignition timing value. If actual ignition
timing is not within specification, see DTC P0335 in G - TESTS W/CODES
article.
All Other Models
1) Ignition timing is controlled by Powertrain Control Module
(PCM) and is not adjustable. Manufacturer provides procedure for
checking timing. On models with distributor, DO NOT attempt to adjust
ignition timing by rotating distributor.
2) Connect scan tool to Data Link Connector (DLC). DLC is
located below dash, near steering column. See Fig. 2. Install a timing
light. Start engine and allow it to idle.
3) Using scan tool, read curb idle speed (RPM). Ensure curb
idle speed is about 750 RPM. Turn engine off. Curb idle speed is
automatically controlled by Idle Air Control (IAC) system. If curb
idle speed is not as specified, see DTC P0505 in G - TESTS W/CODES
article.
CAUTION: MFI system actuator test must be cancelled or test will
continue to run for 27 minutes. Driving vehicle under this
condition may damage engine.
4) Using scan tool, select MFI SYSTEM ACTUATOR TEST, then
select item 17 (BASIC IGNITION TIMING). Read basic ignition timing
value. See IGNITION TIMING SPECIFICATIONS table. If basic ignition
timing is within specification, go to next step. If basic ignition
timing is not within specification, cancel MFI system actuator test.
See DTCS P0100 (except Mirage 1.5L), P0105, P0115 and P0335 in G -
TESTS W/CODES article.
5) Read actual ignition timing value. If actual ignition
timing is not within specification, cancel MFI system actuator test.
See DTCS P0100 (except Mirage 1.5L), P0105, P0115 and P0335 in G -
TESTS W/CODES article.
IDLE SPEED & MIXTURE
* PLEASE READ THIS FIRST *
NOTE: Perform adjustments with engine at normal operating
temperature, cooling fan and accessories off, transmission
in Park or Neutral, and front wheels in straight-ahead
position.
BASIC IDLE SPEED
NOTE: Basic idle speed adjustment information on Eclipse 2.0L
non-turbo engine is not available from manufacturer at time
of publication.
3000GT
1) Ensure vehicle is at normal operating temperature with all
Mirage &
Montero Sport ... Behind Right Side Of Instrument Panel (Glove Box)\
Montero ..................................... Right Front Kick Panel
All Others ................................... Behind Center Console
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NOTE: Components are grouped into 2 categories. The first category
covers INPUT DEVICES, which control or produce voltage
signals monitored by Powertrain Control Module (PCM). The
second category covers OUTPUT SIGNALS, which are components
controlled by PCM.
INPUT DEVICES
Vehicles are equipped with different combinations of input
devices. Not all input devices are used on all models. To determine
input device usage on specific models, see appropriate wiring diagram
in L - WIRING DIAGRAMS article. The following are available input
devices.
Air Conditioning Switch
When A/C is turned on, signal is sent to PCM. With engine at
idle, PCM increases idle speed through Idle Air Control (IAC) motor.
Airflow Sensor Assembly
Assembly is mounted inside air cleaner, and incorporates
barometric pressure sensor, intake air temperature sensor and volume
airflow sensor.
Barometric (BARO) Pressure Sensor
Sensor is incorporated into airflow sensor assembly. Sensor
converts barometric pressure to electrical signal, which is sent to
PCM. PCM adjusts air/fuel ratio and ignition timing according to
altitude.
Camshaft Position (CMP) Sensor
On SOHC engines equipped with a distributor, CMP sensor is
located in distributor. On Eclipse (Turbo) and DOHC V6 engines, sensor\
is located beside camshaft, in front of engine. On all other engines,
CMP sensor is a separate unit mounted in place of distributor. PCM
determines TDC based on pulse signals received from sensor, and then
controls MFI timing.
Closed Throttle Position (CTP) Switch
CTP switch is located in the Throttle Position (TP) sensor.
PCM senses whether accelerator pedal is depressed or not. High voltage
(open) or low voltage (closed) signal is input to PCM, which then
controls Idle Air Control (IAC) motor based on input signal.
Crankshaft Position (CKP) Sensor
CKP sensor is located in distributor on SOHC engines, except
1.5L 4-cylinder with California emissions. On DOHC 4-cylinder, DOHC V6
and 1.5L 4-cylinder engines with California emissions, CKP sensor is
located beside crankshaft, in front of engine. PCM determines
crankshaft position on pulse signals received from sensor, and then
controls MFI timing and ignition timing.
Engine Coolant Temperature (ECT) Sensor
ECT sensor converts coolant temperature to electrical signal
for use by PCM. PCM uses coolant temperature information to control
fuel enrichment when engine is cold.
Heated Oxygen Sensor (HO2S)
pressure regulator diaphragm opens relief valve, allowing pressure to
bleed off through fuel return line, reducing fuel pressure.
As engine manifold vacuum decreases (open throttle), fuel
pressure regulator diaphragm closes valve, preventing pressure from
bleeding off through fuel return line, increasing fuel pressure.
FUEL CONTROL
Fuel Injectors
Fuel is supplied to engine through electronically pulsed
(timed) injector valves located on fuel rail(s). PCM controls amount\
of fuel metered through injectors based on information received from
sensors.
IDLE SPEED
Air Conditioning (A/C) Relay
When A/C is turned on with engine at idle, PCM signals IAC
motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, PCM momentarily opens A/C relay
circuit.
Idle Air Control (IAC) Motor
Motor controls pintle-type air valve to regulate volume of
intake air at idle.
During start mode, PCM controls idle intake air volume
according to Engine Coolant Temperature (ECT) sensor input. After
starting, with idle position switch activated (throttle closed), fast
idle speed is controlled by IAC motor and fast idle air control valve
(if equipped).
When idle switch is deactivated (throttle open), IAC motor
moves to a preset position in accordance with ECT sensor input.
PCM signals IAC motor to increase engine RPM in the following
situations: A/T (if applicable) is shifted from Neutral to Drive, A/C
is turned on, or power steering pressure reaches a preset value.
IGNITION SYSTEMS
DIRECT IGNITION SYSTEM (DIS)
Depending on number of cylinders, ignition system is a 2 or
3-coil, distributorless ignition system. On Eclipse (Turbo) and DOHC
V6 engines, Camshaft Position (CMP) sensor is located beside camshaft,\
in front of engine. On all other engines equipped with DIS, CMP sensor
is a separate unit mounted in place of distributor. On DOHC 4-
cylinder, DOHC V6 and 1.8L 4-cylinder engines with California
emissions, Crankshaft Position (CKP) sensor is located beside
crankshaft, in front of engine. PCM determines TDC based on pulse
signals received from sensors and then controls MFI and ignition
timing.
Power Transistors & Ignition Coils
Based on crankshaft position and CMP sensor inputs, PCM
controls timing and directly activates each power transistor to fire
coils. On 4-cylinder engines, power transistor "A" controls primary
current of ignition coil "A" to fire spark plugs on cylinders No. 1
and No. 4 at the same time. Power transistor "B" controls primary
current of ignition coil "B" to fire spark plugs on cylinders No. 2
and No. 3 at the same time. On V6 engines, companion cylinders No. 1
and 4, 2 and 5, and 3 and 6 are fired together.
On all models, although each coil fires 2 plugs at the same
time, ignition takes place in only one cylinder, since the other
cylinder is on its exhaust stroke when plug fires.
HALL EFFECT IGNITION SYSTEM
This system is equipped with a Hall Effect distributor.
Shutter(s) attached to distributor shaft rotate through distributor
Hall Effect switch, also referred to as a Camshaft Position (CMP)
sensor, which contains a distributor pick-up (a Hall Effect device and
magnet). As shutter blade(s) pass through pick-up, magnetic field is
interrupted and voltage is toggled between high and low. PCM uses this
data along with Crankshaft Position (CKP) sensor data to control
ignition timing and injector pulse width to maintain optimum
driveability.
Power Transistor & Ignition Coil
Power transistor is mounted inside distributor with disc and
optical sensing unit. When ignition is on, ignition coil primary
circuit is energized. As distributor shaft rotates, disc rotates,
triggering optical sensing unit. PCM receives signals from optical
sensing unit. Signals are converted and sent to power transistor,
interrupting primary current flow and inducing secondary voltage.
IGNITION TIMING CONTROL SYSTEM
Ignition timing is controlled by PCM. PCM adjusts timing
based on various conditions such as engine temperature, altitude and
detonation.
EMISSION SYSTEMS
EXHAUST GAS RECIRCULATION (EGR) CONTROL
Federal Emissions (Non-Turbo)
To lower oxides of nitrogen (NOx) exhaust emissions, a non-
computer controlled exhaust gas recirculation system is used. EGR
operation is controlled by throttle body ported vacuum. Vacuum is
routed through vacuum control valve to prevent EGR operation at low
engine temperatures.
Spring pressure holds EGR valve closed during low vacuum
conditions (engine idling or wide open throttle). When vacuum pressure\
increases and overcomes EGR spring pressure, EGR valve is lifted to
allow exhaust gases to flow into intake manifold for combustion.
California Emissions & Turbo
PCM controls EGR operation by activating EGR control solenoid
valve according to engine load. When engine is cold, PCM signals EGR
control solenoid valve to deactivate EGR.
EGR Control Solenoid Valve
Valve denies or allows vacuum supply to EGR valve based on
PCM commands.
EVAPORATIVE CONTROL
Fuel evaporation system prevents fuel vapor from entering
atmosphere. System consists of special fuel tank with vapor separator
tanks (if equipped), vacuum relief filler cap, overfill limiter (2-wa\
y
valve), fuel check valve, thermovalve (if equipped), charcoal
canister, purge control valve, purge control solenoid valve, and
connecting lines and hoses.
Purge Control Solenoid Valve
Spark control systems are designed to ensure the air/fuel
mixture is ignited at the best possible moment to provide optimum
efficiency and power and cleaner emissions.
Ensure vacuum hoses to the distributor, carburetor, spark
delay valves, thermal vacuum switches, etc., are in place and routed
properly. On Computerized Engine Controls (CEC), check for presence of\
required sensors (O2, MAP, CTS, TPS, etc.). Ensure they have not been
tampered with or modified.
Check for visible modification or replacement of the feedback
carburetor, fuel injection unit or injector(s) with a non-feedback
carburetor or fuel injection system. Check for modified emission-
related components unacceptable for use on pollution-controlled
vehicles.
AIR INJECTION SYSTEM (AIS)
Air Pump Injection System (AP)
The air pump is a belt-driven vane type pump, mounted to
engine in combination with other accessories. The air pump itself
consists of the pump housing, an inner air cavity, a rotor and a vane
assembly. As the vanes turn in the housing, filtered air is drawn in
through the intake port and pushed out through the exhaust port. See
Fig. 13 .
Check for missing or disconnected belt, check valve(s),
diverter valve(s), air distribution manifolds, etc. Check air
injection system for proper hose routing.
Fig. 13: Typical Air Pump Injection System
Courtesy of General Motors Corp.
Pulsed Secondary Air Injection (PAIR) System
PAIR eliminates the need for an air pump and most of the
associated hardware. Most systems consists of air delivery pipe(s),
pulse valve(s) and check valve(s). The check valve prevents exhaust
gases from entering the air injection system. See Fig. 14.
Ensure required check valve(s), diverter valve(s), air
distribution manifolds, etc., are present. Check air injection system
for proper hose routing.
CLUTCH PEDAL POSITION SWITCHES
COLD START INJECTORS
CONNECTORS
COOLANT
COOLANT RECOVERY TANKS
COOLING FAN MOTOR MODULES
COOLING FAN MOTOR RELAYS AND MODULES
COOLING FAN MOTOR RESISTORS
COOLING FAN MOTOR SENSORS AND SWITCHES
COOLING FAN MOTOR SWITCHES
COOLING FAN MOTORS
CRANKSHAFT POSITION SENSORS
DECEL VALVES
DEFLECTORS
DIP STICKS AND TUBES
DIP STICK TUBES
DISTRIBUTOR ADVANCES AND RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR BOOTS AND SHIELDS
DISTRIBUTOR CAPS
DISTRIBUTOR RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR ROTORS
DISTRIBUTOR SHIELDS
DISTRIBUTORS
EARLY FUEL EVAPORATION VALVES (HEAT RISER ASSEMBLIES)
EGR COOLERS
EGR EXHAUST MANIFOLD PASSAGES
EGR INTAKE AND EXHAUST MANIFOLD PASSAGES
EGR PLATES AND COOLERS
ELECTRONIC SPARK CONTROL MODULES
ELECTRONIC TRANSMISSION CONTROL DEVICES
ELECTRONIC TRANSMISSION FEEDBACK DEVICES
ENGINE COOLANT TEMPERATURE SENSORS
ENGINE COOLING SYSTEMS
ENGINE COVERS (OIL PAN, VALVE COVER, TIMING COVER)
ENGINE OIL
ENGINE OIL CANISTERS
ENGINE OIL COOLERS (EXTERNAL)
ENGINE OIL DRAIN PLUGS AND GASKETS
ENGINE OIL FILTERS AND CANISTERS
ENGINE OIL GASKETS
ENGINE OIL PRESSURE GAUGES (MECHANICAL)
EVAPORATIVE EMISSION (EVAP) CANISTER FILTERS
EVAPORATIVE EMISSION (EVAP) CANISTER PURGE DEVICES
EVAPORATIVE EMISSION (EVAP) CANISTERS
EVAPORATIVE EMISSION (EVAP) FEEDBACK DEVICES
EXHAUST GAS RECIRCULATION DEVICES
EXHAUST GAS RECIRCULATION FEEDBACK DEVICES
EXPANSION PLUGS
FAN CONTROL SENSORS
FUEL
FUEL ACCUMULATORS AND DAMPERS
FUEL AND COLD START INJECTORS
FUEL DAMPERS
FUEL DELIVERY CHECK VALVES
FUEL DISTRIBUTORS (BOSCH CIS)
FUEL FILLER NECKS AND RESTRICTORS
FUEL FILTERS
FUEL INJECTORS
FUEL LEVEL SENDERS7
FUEL PRESSURE REGULATORS
FUEL PUMPS (IN-TANK AND EXTERNAL, ELECTRICAL OR MECHANICAL)
FUEL RAILS
FUEL RESTRICTORS