Visually/physically inspect the air leakage in intake/exhaust system for the following areas:
-Vacuum hoses for splits, kinks and improper connections.
-Throttle body gasket
-Gasket between intake manifold and cylinder head
-Seals between intake manifold and fuel injectors
-Exhaust system between HO2S and Three way catalyst for air leakage
Visually/physically inspect the restriction in intake/exhaust system for the following areas:
-Air cleaner filter element for excessive dirt or for any foreign objects
-Throttle body inlet for damage or for any foreign objects
-Throttle bore and throttle plate for chocking and for any foreign objects
-Restricted exhaust system
Was a problem found in any of the above areas?
YES
▶ Replace or repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
▶ Go to next step as below
Inspect the leakage in EVAP. system for the following conditions:
Check the EVAP canister for fuel saturation. If the EVAP canister is full of fuel, visually and physically inspect the EVAP and fuel system.Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure. If OK, go to next step.
Remove the manifold side vacuum hose from the EVAP canister purge valve.
Using a hand vacuum pump apply specified vacuum(Approx. 15 in, Hg) to the manifold side of the valve
Does the valve hold vacuum?
YES
▶ Go to next step as below
NO
▶ Repair air leakage and go to "Verification of Vehicle Repair" procedure
Refer to "Signal Waveform & Data" in the "General Information" procedure
Visually/physically inspect the HO2S for the following conditions:
-Ensure that the HO2S is securely installed.
-Silicon contamination. This contamination will be indicated by a white powdery coating on the portion of the sensor exposed to the exhaust stream and this will result in a but false(high) voltage signal
- Fuel, engine coolant or oil contamination
- Use of improper sealant
If contamination is evident on the HO2S, Fix the source of the sensor contamination before replacing the sensor to prevent future contamination. Go to "Verification of Vehicle Repair" procedure.
Visually/physically inspect the MAFS for the following conditions:
-Contamination or deterioration
-Poor connection or damaged harness
Check for an intermittent TPS false signal. TPS signal displayed on a scantool should increase steadily when depressing accelerator pedal after starting.
Verify that the ECM ground connections are clean and properly tightened.
If test result is NG, repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.If OK, go to next step as below.
If the contamination is evident on the HO2S or MAFS. Fix the source of the sensor contamination before replacing the sensor to prevent future contamination.
Check the engine oil level. The oil level should be between the min. and max. marking. Fill to the correct oil level
Check crankcase ventilation valve for improper installation, damaged o-rings and malfunctioning .
Warm up the engine to normal operating temperature
Connect Scantool and note the "SHORT TERM FUEL-B1" parameter on the Scantool data list.
Disconnect and plug the positive crankcase ventilation at the intake manifold side
Monitor the "SHORT TERM FUEL-B1" parameter on the Scantool data list once again.
Specification : The value should remain more or less unchanged
Is the displayed value within the specified value?
YES
▶ Go to next step as below
NO
▶ Check the PCV(Positive Crankcase Ventilation) valve for operation properly. Refer to "EM" group in Workshop Manual. If OK, check that engine oil is diluted with fuel. Change the oil or filter as necessary and go to "Verification of Vehicle Repair" procedure
Fuel Line Pressure Inspection
Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
Install a fuel pressure gage
Inspect fuel pressure with normal idle status
Specification : 338~348kPa(3.45~3.55kg/cm²)
Is fuel pressure within the specified value?
YES
▶ Go to next step as below
NO
▶ Inspect the suspected area. Refer to table as below. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
Condition | Possible Cause | Suspected Area |
Fuel Pressure too low | Clogged fuel filter | Fuel filter |
Fuel leak on the fuel-pressure regulator that is assembled on fuel pump | Fuel Pump(Fuel Pressure Regulator) | |
Fuel Pressure too High | Sticking fuel pressure regulator | Fuel Pump(Fuel Pressure Regulator) |
Fuel Pressure Hold Inspection
Stop the engine and check for a change in the fuel pressure gauge reading.
Specification : After engine stops, the gauge reading should hold for minimum 5 minutes
Is fuel pressure within the specified value?
YES
▶ Visually/physically inspect the engine mechanical problem for the following:
-Worn cylinder
-Worn valve
-Worn piston or piston ring
Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
▶ Inspect the suspected area. Refer to table as below. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
Condition | Possible Cause | Suspected Area |
Fuel pressure drops slowly | Injector leak | Injector |
Fuel pressure drops immediately | Stuck open in check valve of the fuel pump | Fuel pump |
