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DTC P2177
Fuel system too lean at off idle
DETECTION CONDITION
The PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT and the sum total of these fuel trims exceed preprogrammed criteria. PCM determines that fuel system is too lean at off-idle.
Diagnostic support note This is a continuous monitor (Fuel system).
The MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.
FREEZE FRAME DATA is available.
DTC is stored in the PCM memory.
POSSIBLE CAUSE
Misfire
Front HO2S deterioration
Front HO2S heater malfunction
MAF sensor malfunction
Pressure regulator (built-in fuel injection pump) malfunction
Fuel pump malfunction
Fuel filter clogged or restricted
Fuel leakage on fuel line from fuel delivery pipe and fuel pump
Leakage exhaust system
Purge solenoid valve improper operation
Purge solenoid valve malfunction (stuck open)
Purge solenoid hoses improper connection
Air suction in intake-air system
Insufficient engine compression
Variable valve timing control system improper operation.
PCM malfunction
Diagnostic procedure
STEP
INSPECTION
ACTION
1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Fuel system related) been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability.
Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTCS Turn the ignition switch off, then to the ON position (Engine off).
Verify related pending code or stored DTCs.
Is other DTC present?
Yes
If misfire DTC is present, go to Step 8.
If other DTC is present, go to the applicable DTC inspection.
(See DTC TABLE [LF, L3].)
No
If driveability concern is present, go to Step 8.
If not, go to the next step.
4
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA Is DTC P2177 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5
VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION SWITCH TO THE ON POSITION/IDLE) Access APP1, APP2, ECT, MAF, TP and VSS PIDs using M-MDS.
Is there any signal that is far out of specification when the ignition switch is at the ON position and the engine runs?
Yes
Inspect the sensor and excessive resistance in related wiring harnesses.
Repair if necessary.
Then go to Step 17.
No
Go to the next step.
6
VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION Inspect the same PIDs as Step 5 while simulating FREEZE FRAME DATA condition.
Is there any signal which causes drastic changes?
Yes
Inspect the sensor and related wiring harnesses repair or replace it.
Then go to Step 17.
No
Go to the next step.
7
VERIFY CURRENT INPUT SIGNAL STATUS OF FRONT HO2S Access O2S11 PID using M-MDS.
Check PID under following accelerator pedal condition (in PARK (ATX) or NEUTRAL (MTX)).
Is PID reading normal?
Less than 1 mAwhen accelerator pedal is suddenly depressed (rich condition).
More than 1 mAjust after release of accelerator pedal (lean condition).
Yes
Go to the next step.
No
Inspect for followings;
Air suction at following due to cracks, damages and loosing parts:
From air cleaner to throttle body
From throttle body to dynamic chamber
From dynamic chamber and intake manifold
Vacuum hoses
NOTE:
Engine speed may change when rust penetrating agent is sprayed on air suction area.
Exhaust gas leakage between exhaust manifold and front HO2S.
Loose installation of front HO2S.
If there are no malfunctions detected, replace FRONT HO2S.
If there are malfunctions detected, repair or replace malfunctioning part.
Then go to Step 17.
8
VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR Connect the M-MDS to the DLC-2.
Start the engine.
Access the MAF PID.
Verify that the MAF PID changes quickly according to engine speed.
Is the PID normal?
Yes
Go to the next step.
No
Replace MAF/IAT sensor, then go to Step 17.
9
INSPECT FOR EXCESSIVE AIR SUCTION OF INTAKE AIR SYSTEM Visually inspect for loosen, cracks or damages hoses on intake-air system.
Is there any malfunction?
Yes
Repair or replace source of air suction, then go to Step 17.
No
Go to the next step.
10
INSPECT PURGE SOLENOID OPERATION Perform Purge Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION[LF, L3].)
Does the purge control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to inspection result, then go to Step 17.
11
INSPECT FUEL LINE PRESSURE Turn the ignition switch off.
Inspect the fuel line pressure.
(See FUEL LINE PRESSURE INSPECTION[LF, L3].)
Is the fuel line pressure normal?
Yes
Go to Step 12.
No
If the fuel pressure is too high, replace fuel pump unit, then go to Step 17.
If the fuel line pressure is low, go to the next step.
12
INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE Visually inspect fuel line for any leakage.
Is fuel leakage found?
Yes
Replace suspected fuel line, then go to Step 17.
No
Inspect for foreign materials or stain inside fuel filter (low-pressure).
If for foreign materials or stain inside fuel filter (low-pressure), clean of fuel tank and filter.
Then go to Step 17.
13
INSPECT IGNITION SYSTEM Perform spark test.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION[LF, L3].)
Is strong blue spark visible at each cylinder?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to spark test result, then go to Step 17.
14
INSPECT ENGINE COMPRESSION Inspect the engine compression.
(See COMPRESSION INSPECTION [LF, L3].)
Is it normal?
Yes
Go to the next step.
No
Implement the engine overhaul for repairs, then go to Step 17.
15
INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION Inspect variable valve timing control system operation.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION[LF, L3].)
Does variable valve timing control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to inspection results, then go to Step 17.
16
INSPECT FUEL INJECTOR OPERATION Remove the fuel injector.
Inspect the fuel injector (resistance, injection amount).
(See FUEL INJECTOR INSPECTION[LF, L3].)
Is the fuel injector normal?
Yes
Go to the next step.
No
Replace the fuel injector, then go to the next step.
17
VERIFY TROUBLESHOOTING OF DTC P2177 COMPLETED Make sure to reconnect all disconnected connectors.
Clear the DTCs and long term fuel trim stored in the PCM using the following procedure:
Disconnect the negative battery cable.
Depress the brake pedal for at least 5 s.
Connect the negative battery cable.
Perform the KOER self-test or the PCM Adaptive Memory Produce Drive Mode.
(See OBD-II DRIVE MODE[LF, L3].)
Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION[LF, L3].)
No
Go to the next step.
18
VERIFY AFTER REPAIR PROCEDURE Perform “AFTER REPAIR PROCEDURE”.
(See AFTER REPAIR PROCEDURE[LF, L3].)
Is there any DTC present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [LF, L3].)
No
Troubleshooting completed.