Infiniti QX4 (R50). Manual — part 210
4
CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-39.
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-39.
At idling:
When fuel pressure regulator valve vacuum hose is connected.
235 kPa (2.4 kg/cm
2
, 34 psi)
When fuel pressure regulator valve vacuum hose is disconnected.
294 kPa (3.0 kg/cm
2
, 43 psi)
OK or NG
OK
©
GO TO 6.
NG
©
GO TO 5.
5
DETECT MALFUNCTIONING PART
Check the following.
I
Fuel pump and circuit (Refer to EC-625.)
I
Fuel pressure regulator (Refer to EC-40.)
©
Repair or replace.
6
CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in MODE 1 with GST.
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
OK or NG
OK
©
GO TO 7.
NG
©
Check connectors for rusted terminals or loose connections in the mass air flow sensor
circuit or engine grounds. Refer to EC-150.
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BT
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SC
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IDX
DTC P0172 (RIGHT, -B1), P0175 (LEFT, -B2) FUEL INJECTION SYSTEM
FUNCTION (RICH)
Diagnostic Procedure (Cont’d)
EC-307
7
CHECK FUNCTION OF INJECTORS
With CONSULT-II
1. Start engine.
2. Perform “POWER BALANCE” in “ACTIVE TEST” mode with CONSULT-II.
SEF070Y
3. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT-II
1. Start engine.
2. Listen to each injector operating sound.
MEC703B
Clicking noise should be heard.
OK or NG
OK
©
GO TO 8.
NG
©
Perform trouble diagnosis for “INJECTORS”, EC-617.
8
CHECK INJECTOR
1. Remove injector assembly. Refer to EC-41.
Keep fuel hose and all injectors connected to injector gallery.
2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Disconnect injector harness connectors left bank (for DTC P0172), right bank (for P0175).
The injector harness connectors on right bank (for P0172), left bank (for P0175) should remain connected.
4. Disconnect all ignition coil harness connectors.
5. Prepare pans or saucers under each injectors.
6. Crank engine for about 3 seconds.
Make sure fuel does not drip from injector.
OK or NG
OK (Does not drip.)
©
GO TO 9.
NG (Drips.)
©
Replace the injectors from which fuel is dripping. Always replace O-ring with new one.
9
CHECK INTERMITTENT INCIDENT
Refer to “TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT”, EC-140.
©
INSPECTION END
DTC P0172 (RIGHT, -B1), P0175 (LEFT, -B2) FUEL INJECTION SYSTEM
FUNCTION (RICH)
Diagnostic Procedure (Cont’d)
EC-308
SEF751UA
Component Description
NBEC0177
The fuel tank temperature sensor is used to detect the fuel tem-
perature inside the fuel tank. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the fuel
temperature input. The sensor uses a thermistor which is sensitive
to the change in temperature. The electrical resistance of the ther-
mistor decreases as temperature increases.
SEF012P
<Reference data>
Fuel temperature
°C (°F)
Voltage*
V
Resistance
k
Ω
20 (68)
3.5
2.3 - 2.7
50 (122)
2.2
0.79 - 0.90
*: These data are reference values and are measured between ECM terminal 92
(Fuel tank temperature sensor) and body ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM’s
transistor. Use a ground other than ECM terminals, such as
the ground.
On Board Diagnosis Logic
NBEC0178
Malfunction is detected when an excessively high or low voltage is
sent to ECM, rationally incorrect voltage is sent to ECM, compared
with the voltage signals from engine coolant temperature sensor
and intake air temperature sensor.
Possible Cause
NBEC0489
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Fuel tank temperature sensor
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IDX
DTC P0180 FUEL TANK TEMPERATURE SENSOR
Component Description
EC-309
DTC Confirmation Procedure
NBEC0179
NOTE:
If “DTC Confirmation Procedure” has been previously conducted,
always turn ignition switch “OFF” and wait at least 10 seconds
before conducting the next test.
SEF174Y
WITH CONSULT-II
NBEC0179S01
1)
Turn ignition switch “ON”.
2)
Select “DATA MONITOR” mode with CONSULT-II.
3)
Wait at least 10 seconds.
If the result is NG, go to “Diagnostic Procedure”, EC-312.
If the result is OK, go to following step.
4)
Check “COOLAN TEMP/S” value.
If “COOLAN TEMP/S” is less than 60°C (140°F), the result will
be OK.
If “COOLAN TEMP/S” is above 60°C (140°F), go to the follow-
ing step.
5)
Cool engine down until “COOLAN TEMP/S” is less than 60°C
(140°F).
6)
Wait at least 10 seconds.
7)
If 1st trip DTC is detected, go to “Diagnostic Procedure”,
EC-312.
WITH GST
NBEC0179S02
Follow the procedure “With CONSULT-II” above.
DTC P0180 FUEL TANK TEMPERATURE SENSOR
DTC Confirmation Procedure
EC-310
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