Mitsubishi 3000GT Service Manual page 127

MULTIPORT FUEL INJECTION - Troubleshooting
DIAGNOSTIC DETECTION LOGIC
Fault ID
Heated Oxygen Sensor (front) <Except
1994 and Later California model> / Left
11
Bank Heated Oxygen Sensor (front)
cl994 and Later California model>
Background
The oxygen sensor converts the oxygen density in the exhaust
l
gas to a voltage and outputs it.
The engine control module checks the change of an oxygen
l
sensor output voltage (Lean/Rich) in the air/fuel ratio closed
loop control.
Range of Check
3 minutes have passed after engine was started.
l
Engine coolant temperature is approx. 80°C (176°F) or more.
l
Intake air temperature is 20-50°C (68-122°F).
l
Engine speed is approx. 1,900-2,200 r/min.
l
Vehicle is moving at constant speed on a flat, level road surface.
l
Set Conditions
The oxygen sensor output voltage does not cross specified voltage
for specified seconds.
Fault ID
Volume Air Flow Sensor
12
Background
While the engine is running, the volume air flow sensor outputs
l
a pulse signal which corresponds to the volume of air flow.
The engine control module checks whether the frequency of
l
this signal output by the volume air flow sensor while the engine
is running is at or above the set value.
Range of Check
Engine speed is 500 r/min or more.
Set Conditions
Sensor output frequency is 3 Hz or less for 4 seconds.
Title
Title
TSB Revision
Effect
Limp-in Oxygen sensor deteriorated.
l
Open or shorted oxygen
l
Air/fuel ratio closed loop
sensor
control is not performed.
connector.
Injector failed.
l
Air intake.
l
Engine control module failed.
l
Effect
Volume air flow sensor failed.
Limp-in
l
Open or shorted volume air
l
(a) Uses the throttle
flow sensor circuit, or loose
position sensor sig-
connector.
nal and engine
Engine control module failed.
l
signal
speed
(crankshaft position
sensor signal) for
basic injector drive
time and basic igni-
tion timing from the
pre-set mapping.
(b) Fixes the IAC motor
in the appointed
position so idle air
control is not per-
formed.
Probable causes
circuit, or
loose
Probable causes