System Inspection

Visual Inspection
1. Check the air hose between MAFS and throttle body is torn or installation.
2. Check deformation, crack or installation of throttle valve (body)
3. Has a problem been found?
  YES
  1. Substitute with a known-good Air hose or throttle body and check for proper operation.
  If the problem is corrected, replace air hose or throttle body and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.
  
  NO
  1. Go to 4 "Check MAFS" as follows.
4. Check MAFS
  1. IG "OFF" and install a scantool
  2. ENG "ON" and monitor "MAFS" data on the service data.
  3. Monitor signal waveform at signal terminal of MAFS with scantool.
    1. Specification : Signal waveform will be displayed as follows. (Be aware that the signal of MAFS is not voltage display but frequency display.)
    Fig 1: MAFS Signal Waveform (1 Of 2)
    Courtesy of HYUNDAI MOTOR CO.
    
    Fig 2: MAFS Signal Waveform (2 Of 2)
    Courtesy of HYUNDAI MOTOR CO.
  4. Are both service data and signal waveform dispayed correctly?
    YES
    1. Go to VERIFICATION OF VEHICLE REPAIR procedure.
    NO
    1. 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.

Check air leakage
1. Visually/physically inspect the air leakage in intake/exhaust system for following items
  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
2. Has a problem found in this procedure?
  YES
  
  Repair or replace it which has a problem, and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
  
  NO
  
  Go to 2 "Check the fuel line" as follows

Check the fuel line

Check the fuel line for following items
Connector connection state

Damage/connection state for vacuum hoses connected to fuel line

Bent/pressed/twisted fuel line or fuel leakage
Has a problem found in this procedure?
YES

Repair or replace it which has a problem, and Go to VERIFICATION OF VEHICLE REPAIR procedure.

NO

Go to 3 "Check fuel pressure" as follows

Check fuel pressure

NOTE:

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 personal injury or fire 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.
1. Specifications: 374.6 ~ 384.4 kPa (3.82 ~ 3.92 kg/cm² , 54.3 ~ 55.8 psi)

Is the measured fuel pressure within specifications?

YES

Go to COMPONENT INSPECTION procedure.

YES

Repair or replace according to the below table. And then, Go to VERIFICATION OF VEHICLE REPAIR procedure.

PROBLEM SYMPTOMS

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