Diagnosis Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).

Fig 1: Checking Exhaust Gas Leak

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OK or NG 

OK: GO TO 2.

NG: Repair or replace malfunctioning part.

1. Listen for an intake air leakage after the mass air flow sensor.
2. Check PCV hose connection.

OK or NG 

OK: GO TO 3.

NG: Repair or replace malfunctioning part.

1. Turn ignition switch OFF.
2. Disconnect corresponding air fuel ratio (A/F) sensor 1 harness connector.
   Fig 2: Identifying Air Fuel Ratio (A/F) Sensor 1 Harness Connector

   Courtesy of NISSAN NORTH AMERICA, INC.
3. Disconnect ECM harness connector.
4. Check harness continuity between A/F sensor 1 terminals and ECM terminals as per the following. Refer to WIRING DIAGRAM .

   	A/F sensor 1 terminal	ECM terminal
   Bank 1	1	35
   	2	56
   Bank 2	1	16
   	2	75

   Continuity should exist  .

5. Check harness continuity between the following terminals and ground.

   Refer to WIRING DIAGRAM .

   Bank 1		Bank 2
   A/F sensor 1 terminal	ECM terminal	A/F sensor 1 terminal	ECM terminal
   1	35	1	16
   2	56	2	75

   Continuity should not exist  .

6. Also check harness for short to power.

OK or NG 

OK: GO TO 4.

NG: Repair open circuit or short to ground or short to power in harness or connectors.

1. Release fuel pressure to zero. Refer to "FUEL PRESSURE CHECK ".
2. Install fuel pressure gauge and check fuel pressure. Refer to "FUEL PRESSURE CHECK ".

At idling: Approximately 350 kPa (3.57 kg/cm ²  , 51 psi) 

OK or NG 

OK: GO TO  6.

NG: GO TO 5.

Check the following.

• Fuel pump and circuit (Refer to "DIAGNOSIS PROCEDURE ".)
• Fuel pressure regulator (Refer to "FUEL PRESSURE CHECK ".)
• Fuel lines (Refer to "CHECKING FUEL LINE ".)
• Fuel filter for clogging

Repair or replace malfunctioning part.

With CONSULT

1. Install all removed parts.
2. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT.

3.0 - 9.0 g.m/sec: At idling 

9.0 - 28.0 g.m/sec: At 2, 500 RPM 

With GST 

1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.

3.0 - 9.0 g.m/sec: at idling 

9.0 - 28.0 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 grounds. Refer to "DIAGNOSIS PROCEDURE ".

With CONSULT 

1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT.
3. Check that each circuit produces a momentary engine speed drop.

Without CONSULT 

1. Start engine.
2. Listen to each fuel injector operating sound.

Clicking noise should be heard  .

Fig 3: Checking Fuel Injector Operating Sound

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OK or NG 

OK: GO TO 8.

NG: Perform trouble diagnosis for FUEL INJECTOR, refer to "DIAGNOSIS PROCEDURE ".

1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch OFF.
3. Disconnect all fuel injector harness connectors.
4. Remove fuel injector gallery assembly. Refer to "REMOVAL AND INSTALLATION ".

   Keep fuel hose and all fuel injectors connected to fuel injector gallery.

5. For DTC P0171, reconnect fuel injector harness connectors on bank 1.

   For DTC P0174, reconnect fuel injector harness connectors on bank 2.

6. Disconnect all ignition coil harness connectors.
7. Prepare pans or saucers under each fuel injector.
8. Crank engine for approximately 3 seconds.

For DTC P0171, check that fuel sprays out from fuel injectors on bank 1.

For DTC P0174, check that fuel sprays out from fuel injectors on bank 2.

Fuel should be sprayed evenly for each fuel injector  .

Fig 4: Checking Fuel Injector

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OK or NG 

OK: GO TO 9.

NG: Replace fuel injectors from which fuel does not spray out. Refer to FUEL INJECTOR AND FUEL TUBE . Always replace O-ring with new ones.

Refer to "INTERMITTENT INCIDENT ".

>> INSPECTION END