2.
Are there the DTCs above-mentioned?
▶ Do all repairs associated with those codes before proceeding with this procedure.
▶ Go to "System Inspection" procedure
In order to provide the best possible combination of drivability, fuel economy and emission control, the ECM uses a closed loop air/fuel metering system. The ECM monitors the HO2S signal voltage and adjusts fuel delivery based it in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The ECM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The ECM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition.
Checking the fuel trime value under detecting condition, if its average exceeds the limit over certain period, PCM sets P0175. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause | |||||
DTC Strategy | ● Monitor the fuel trim value | ● Blocking of intake system ● Fuel leakage in injector ● Improper fuel pressure | |||||
Enable Conditions | ● Engine warm-up sufficiently ● Drive at a steady speed over 5 minutes ( Vehicle speed ≤ 130km/h) ● 60℃(140℉) ≤ Engine coolant temperature ≤ 115℃(239℉) ● No disabling faults (DTCs related to HO2S, purge valve,catalyst ) | ||||||
Threshold value | ● Average of short term fuel trim ＜ 1.2 and Average of long term fuel trim＜ 0.8 | ||||||
Diagnosis Time | ● Continuous | ||||||
MIL On Condition | ● 2 Driving Cycles | ||||||
Monitor DTCs related to MAFS, MAPS, ECTS, Injector or CVVT items with scantool.
Are there the DTCs above-mentioned?
▶ Do all repairs associated with those codes before proceeding with this procedure.
▶ Go to "System Inspection" procedure
Check blocking of intake system
Visually/physically inspect the blocking in intake system for following items
▶ Throttle body gasket and damage
▶ Blocking in intake manifold and injector caused by any foreign substance
Has a problem found?
▶ Repair or replace it, and go to "Verification of Vehicle Repair" procedure.
▶ Go to " Check fuel pressure" as follows.
Check fuel pressure
Be cautious that Fuel is explosive and an empty fuel tank can still contain explosive gases.When working on fuel system make sure to supply adequate ventilationto the work area. Do not smoke, and keep sparks and open flames away.
The fuel system remains under pressure when the engine is not running. Release fuel systempressure before disconnecting any fuel line to reduce the chance of presonal injury orfire damage to vehicle components.
IG "OFF" and disconnect Fuel Pump Relay in Junction Box.
Start-up and wait until it stops itself.
IG "OFF" and connect Fuel Pump Relay.
Install the fuel pressure gauge to the delivery pipe with the fuel pressure gauge adaptor.
Activate the fuel pump, and with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.
Measure the fuel pressure at idle.
Specification : 374.6 ~ 384.4 kPa(3.82 ~ 3.92 ㎏/㎠, 54.3 ~ 55.8 psi)
Is the measured fuel pressure within specifications ?
▶ Go to "Check fuel leakage in injector" as follow.
▶ Repair or replace according to the below table. And then, go to " Verification of VehicleRepair"procedure.
Condition | Possible Cause |
Fuel Pressure is too low | Fuel filter,fuel pressure regulator, in-tank fuel hose or the fuel pump |
Fuel Pressure is too high | Fuel pressure regulator, hose or pipe |
Check fuel leakage in injector
IG "OFF" after checking the fuel pressure test.
Stop engine and check for a change in the fuel pressure gauge reading for 5 minutes.
Specification : After engine stops, fuel gauge reading is maintained for 5 minutes.
Is the fuel gauge reading maintained ?
▶ Clear DTC and Test-drive under enable conditions above-mentioned. After the test, If this DTC is set, go to "Inspection & Repair" procedure. If not, troubleshooting is completed.
▶ There is a fuel leakage in injector. Replace it, and go to " Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
Read "DTC Status" parameter
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC.
▶ Go to the applicable troubleshooting procedure.
