Visually/physically inspect the air leakage in intake/exhaust system as following items,
If OK, go to next step.
If NG, repair as necessary and go to "Verification of Vehicle Repair" procedure.
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
Check for air leakage in EVAP. Purge control valve.
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 "Fuel System Inspection" procedure.
NO
▶ Repair air leakage and go to "Verification of Vehicle Repair" procedure.
Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
Install a fuel pressure gauge.
Start engine and let it idle. With the vacuum hose from the fuel pressure regulator disconnected, inspect fuel pressure.
Specification : 330~350kPa(3.30~3.50 ㎏/㎠, 47~50 psi)
Is fuel pressure within the specification?
YES
▶ Go to "Fuel Injector Inspection" procedure as below
NO
▶ Repair as necessary refer to inspection note as below and go to "Verification of Vehicle Repair" procedure.(Inspection Note)
Check if fuel line pressure decreases when accelerating quickly.
If it does, check fuel pump maximum pressure. If pressure is OK, check fuel line and filter for clogging
If fuel pressure is lower than specification : Check for fuel line pressure while pinching fuel return hose.
If pressure quickly increases, check pressure regulator
If pressure gradually increases, check for clogging between fuel pump and pressure regulator. If hose is not clogged, check fuel pump maximum pressure.
If fuel pressure is higher than specification : Is fuel line clogged?
If it is not, replace pressure regulator.
If it is, replace it.
Check the fuel injectors for clogging or any restrictions.
Test Condition : Ignition "OFF".
Specification : No clogging and restriction.
Is the fuel injector OK?
YES
▶ Visually/physically inspect the engine mechanical problem. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO
▶ Check injector for contamination, deterioration, or damage. Substitute with a known-good injector and check for proper operation. If the problem is corrected, replace injector and then go to "Verification of Vehicle Repair" procedure.
