MULTIPORT FUEL INJECTION
(MFI) |
GENERAL INFORMATION
FUEL INJECTION CONTROL


IDLE SPEED CONTROL
IGNITION TIMING CONTROL

OTHER CONTROL FUNCTIONS
1. |
Fuel Pump Control :
Turns the fuel pump relay ON so that current
is supplied to the fuel pumpwhile the engine is cranking or
running. |
2. |
A/C Compressor Clutch Relay Control
:
Turns the compressor clutch of the A/C ON and
OFF. |
3. |
Fan Relay Control :
The radiator fan and condenser fan speeds are
controlled in response to theengine coolant temperature and vehicle
speed. |
4. |
Evaporative Emission Purge Control (Refer to
GROUP EC). |
DIAGNOSTIC TEST MODE
• |
When an abnormality is detected in one of the
sensors or actuators relatedto emission control, the CHECK
ENGINE/MALFUNCTION INDICATOR LAMP illuminatesas a warning to the
driver. |
• |
When an abnormality is detected in one of the
sensors or actuators, a diagnostictrouble code corresponding to the
abnormality is output. |
• |
The RAM data inside the PCM that is related to
the sensors and actuators canbe read by means of the scan tool. In
addition, the actuators can be controlledunder certain
circumstances. |
HOW TO COPE WITH INTERMITTENT
MALFUNCTIONS
1. |
Ask the customer about the
malfunction.
Ask what it feels like, what it sounds like,
etc. Then ask about driving conditions,weather, frequency of
occurrence, and so on. |
2. |
Determine the conditions from the customer's
responses.
Typically, almost all intermittent
malfunctions occur from conditions likevibration, temperature and/or
moisture change, poor connections. From thecustomer's replies, it
should be deduced which condition
exists. |
3. |
Use the simulation test
In the cases of vibration or poor connections,
use the simulation tests belowto attempt to duplicate the customer's
complaint. Determine the most likelycircuit(s) and perform the
simulation tests on the connectors and parts ofthat circuit(s). Be
sure to use the inspection procedures provided for diagnostictrouble
codes and trouble symptoms. For temperature and/or moisture
conditionsrelated intermittent malfunctions, using common sense, try
to change the conditionsof the suspected circuit components, then
use the simulation tests below. |
4. |
Verify that the intermittent malfunction is
eliminated.
Repair the malfunctioning part and try to
duplicate the condition(s) againto verify that the intermittent
malfunction has been eliminated. |
• |
Shake the connector up-and-down,
right-and-left. |
• |
Shake the wiring harness up-and-down,
right-and-left. |
• |
Vibrate the part or
sensor. |
SERVICE POINTS IN INSPECTING A BLOWN
FUSE
• |
Harness being crushed by the vehicle
body. |
• |
Damage to the outer casing of the harness due
to wear or heat. |
• |
Water getting into the connector or
circuitry. |
• |
Human error (mistakenly shorting a circuit,
etc.). |
INSPECTING THE MFI SYSTEM
1. |
Engine is hard to start or does not start at
all |
ON-BOARD DIAGNOSTICS
• |
Diagnostic trouble codes are set as
follows:
After the PCM first detects a malfunction, a
diagnostic trouble code is recorded when the engine is restarted and
the same malfunction is re-detected. (Themalfunction is detected in
driving cycle). However, for fuel system rich/lean misfiring, a
diagnostic trouble code is recorded on the first detection of the
malfunction. |
• |
Erasing diagnostic trouble codes:
After recording the diagnostic trouble code,
if the PCM does not re-detect the malfunction for 40 driving cycles,
the diagnostic trouble code will be erased from the PCM memory.
However, for fuel system rich/lean or misfiring,the diagnostic
trouble code will be erased if both of the following conditions are
met: |
-
|
When driving conditions (engine speed,
engine coolant temperature, etc.) are identical to those when
the malfunction was first
recorded. |
-
|
When the PCM does not re-detect the
malfunction for 80 driving
cycles. | |
A "driving cycle" is complete as soon as the
vehicle goes into closed-loop
operation. |
• |
Air flow sensor (MAF
sensor) |
• |
Intake Air Temperature Sensor (IAT
sensor) |
• |
Engine Coolant Temperature Sensor (ECT
sensor) |
• |
Throttle Position Sensor
(TPS) |
• |
Rear Oxygen Sensor
Heater |
• |
Front Oxygen Sensor
Heater |
• |
Crankshaft Position Sensor (CKP
sensor) |
• |
Camshaft Position Sensor (CMP
sensor) |
• |
Evaporative Emission Control
System |
• |
Vehicle Speed Sensor
(VSS) |
• |
PCM

|
1. |
After turning the ignition key on, check that
the light illuminates for 5 seconds without the engine
running. |
2. |
If the light does not illuminate, check for an
open circuit in the harness,blown fuse and blown
bulb. |
•
|
When battery voltage is excessively low,
diagnostic trouble codes can not be read. Be sure to check the
battery for voltage and the charging system before starting
the test. |
•
|
Codes are erased if the battery or the
PCM connector is disconnected. Do not disconnect the battery
before the diagnostic trouble codes are completely read and
recorded. | |
1. |
Turn OFF the ignition
switch. |
2. |
Connect the scan tool to the data link
connector on the lower crash pad. |
3. |
Turn ON the ignition
switch. |
4. |
Use the Hi-Scan Pro to check the diagnostic
trouble code. |
5. |
Repair the faulty part from the diagnosis
chart. |
6. |
Erase the diagnostic trouble
code. |
7. |
Disconnect the Hi-Scan Pro.

|
TROUBLESHOOTING
DIAGNOSTIC TROUBLESHOOTING FLOW
