MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-298
STEP 9. Using the oscilloscope, check the injector.
(1) Disconnect the injector connector B-02 <No. 2 cylinder> or
B-06 <No. 4 cylinder> or B-25 <No. 6 cylinder> and
connect the test harness special tool (MB991348)
inbetween. (All terminals should be connected)
(2) Connect the oscilloscope probe to the injector side
connector terminal 2.
NOTE: When measuring with the ECM or PCM side con-
nector, connect an oscilloscope probe to the each of the fol-
lowing terminals.
.
•
ECM or PCM terminal 9 when checking No. 2 cylinder.
•
ECM or PCM terminal 2 when checking No. 4 cylinder.
•
ECM or PCM terminal 25 when checking No. 6 cylinder.
(3) Start the engine and run at idle.
(4) Measure the waveform.
•
The waveform should show a normal pattern similar to
the illustration.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the waveform normal?
YES :
It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points
NO :
Replace the ECM or PCM. Then go to Step 10.
STEP 10. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to
Procedure 6
−
Other Monitor
(2) Check the diagnostic trouble code (DTC).
Q: Is the DTC P0202, P0204, P0206 is output?
YES :
Retry the troubleshooting.
NO :
The inspection is complete.
DTC P0300: Random/Multiple Cylinder Misfire Detected
.
Random Misfire Circuit
•
Refer to DTC P0201, P0203, P0205
−
Injector
Circuit
•
Refer to DTC P0202, P0204, P0206
−
Injector
Circuit
.
CIRCUIT OPERATION
•
Refer to DTC P0201, P0203, P0205
−
Injector
Circuit
•
Refer to DTC P0202, P0204, P0206
−
Injector
Circuit
.
TECHNICAL DESCRIPTION
•
If a misfire occurs while the engine is running, the
engine speed changes for an instant.
•
The ECM <M/T> or PCM <A/T> checks for such
changes in engine speed.
.
DTC SET CONDITIONS
Check Conditions
•
Engine speed is between 440 and 6,000 r/min.
•
Engine coolant temperature is higher than
−
10
°
C
(14
°
F).
•
Intake air temperature is higher than
−
10
°
C
(14
°
F).
AK102980
1 2
INJECTOR
CONNECTOR
MB991348
AB
OSCILLOSCOPE
AKX01557 AB
A
NORMAL WAVEFORM
A:INJECTOR DRIVE TIME