2.
Are related DTCs present?
▶ 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 PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts fuel delivery as needed. 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 PCM 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 PCM 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 trim value at idle under detecting condition, if its average exceeds the limit over certain period, PCM sets P2188. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycles.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Monitor the fuel trim value at idle | ● MAFS ● Blocking of intake system ● Fuel leakage in injector ● Improper fuel pressure |
EnableConditions | ● Engine at operating temperature ● Engine running under Idle state over 5 minutes ● 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 ＜ 1.5 and Average of long term fuel trim ＜ 0.76 | |
DiagnosisTime | ● Continuous | |
MIL On Condition | ● 2 Driving Cycles |
Monitor DTCs related to HO2S, MAFS, MAPS, ECTS, PCSV, Injector or CVVT items with scantool.
Are related DTCs present?
▶ 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 intake/exhaust system for following items
▶ Throttle body gasket and damage
▶ Blocking in intake manifold and injector caused by any foreign substance
Has a problem been 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 ventilation to 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 system pressure before disconnecting any fuel line to reduce the chance of presonal injury or fire damage to vehicle components.
IG "OFF" and disconnect Fuel Pump Relay in Junction Box.
Start the engine and wait until the engine stalls.
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" procedure.
▶ Repair or replace according to the below table. And then, go to " Verification of Vehicle Repair"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 ?
▶ Go to "Check MAFS" as follows.
▶ Replace injector, and go to "Verification of Vehicle Repair" procedure.
Check MAFS
IG "OFF" and install a scantool.
ENG "ON" and monitor "MAFS" data on the service data.
Monitor signal waveform at signal terminal of MAFS with scantool.
Specification :Signal waveform will be displayed as follows.
(Be aware that the signal of MAFS is not voltage display but frequency display.)
Are both service data and signalwave form dispayed correctly ?
▶ 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.
▶ Substitute with a known - good MAFS and check for proper operation.
If the problem is corrected, replace MAFS and go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "DTC" button.
Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". 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.
