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 | |
| •
|
Blocking of intake
system |
| •
|
Fuel leakage in
injector |
|
EnableConditions
|
| •
|
Engine at operating
temperature |
| •
|
Engine running under Idle state over 5
minutes |
| •
|
60°C(140°F) ≤ Engine coolant temperature
≤ 115°C(239°F) |
| •
|
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
|
|
MIL On
Condition
|
|
| 1. |
Monitor DTCs related to HO2S, MAFS, MAPS,
ECTS, PCSV, Injector or CVVT items with
scantool. |
| 2. |
Are related DTCs present?
|
|
▶ Do all
repairs associated with those codes before proceeding with
this procedure.
|
|
|
▶ Go to
"System Inspection"
procedure
|
|
| 1. |
Check blocking of intake system
| (1) |
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 |
| (2) |
Has a problem been found?
|
|
▶
Repair or replace it, and go to "Verification of Vehicle
Repair" procedure.
|
|
|
▶ Go
to " Check fuel pressure" as
follows.
|
| |
| 2. |
Check fuel pressure
| 1. |
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. |
| 2. |
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. | |
| (1) |
IG "OFF" and disconnect Fuel Pump Relay
in Junction Box. |
| (2) |
Start the engine and wait until the
engine stalls. |
| (3) |
IG "OFF" and connect Fuel Pump
Relay. |
| (4) |
Install the fuel pressure gauge to the
delivery pipe with the fuel pressure gauge
adaptor. |
| (5) |
Activate the fuel pump, and with fuel
pressure applied, check that there is no fuel leakage from the
pressure gauge or connection
part. |
| (6) |
Measure the fuel pressure at
idle.
Specification : 374.6
~ 384.4 kPa(3.82 ~ 3.92 kg/cm², 54.3 ~ 55.8
psi)
| |
| (7) |
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
|
| |
| 3. |
Check fuel leakage in injector
| (1) |
IG "OFF" after checking the fuel
pressure test. |
| (2) |
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.
| |
| (3) |
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 amp;amp; Repair" procedure. If not,
troubleshooting is completed.
|
|
|
▶
There is a fuel leakage in injector. Replace it, and go
to " Verification of Vehicle Repair"
procedure.
|
| |
| Verification Of Vehicle
Repair |
After a repair, it is
essential to verify that the fault has been corrected.
| 1. |
Connect scantool and select "DTC"
button. |
| 2. |
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 |
| 3. |
Read "DTC Status"
parameter |
| 4. |
Is parameter displayed "History(Not Present)
fault"?
|
|
▶ System
performing to specification at this time. Clear the
DTC
|
|
|
▶ Go to the
applicable troubleshooting
procedure.
|
|
