TROUBLE DIAGNOSES — Diagnostic Table (Cont'd) — Symptom & Condition 14: Poor driveability — stumble (while accelerating)
EF & EC-52flowchartDiagnostic Table (Cont'd)
SYMPTOM & CONDITION 14 — Poor driveability — stumble (while accelerating)
Possible Causes vs. Check Steps Matrix
SPECIFICATIONS
Possible CausesMixture ratio
1
2
3O
4
5O
6O
7
8O
SPECIFICATIONS
Possible CausesFuel pressure
1
2
3
4
5O
6O
7
8
FUEL SYSTEM
Possible CausesFuel filter (clogged)
1
2
3
4
5
6
7O
8
FUEL SYSTEM
Possible CausesFuel line (clogged)
1
2
3
4
5
6
7O
8
FUEL SYSTEM
Possible CausesInjectors (clogged)
1
2
3
4
5
6
7O
8
IGNITION SYSTEM
Possible CausesPower transistor
1O
2O
3
4
5
6
7
8
IGNITION SYSTEM
Possible CausesIgnition coil
1O
2O
3
4
5
6
7
8
IGNITION SYSTEM
Possible CausesSpark plugs (ignition leaks, improper gap)
1
2O
3
4
5
6
7
8
INTAKE SYSTEM
Possible CausesAir duct (leaks)
1
2
3
4O
5
6
7
8
CONTROL SYSTEM
Possible CausesCrank angle sensor
1
2
3O
4
5
6
7
8O
CONTROL SYSTEM
Possible CausesAir flow meter
1
2
3
4
5
6
7
8O
CONTROL SYSTEM
Possible CausesEngine temperature sensor
1
2
3O
4
5
6
7
8O
CONTROL SYSTEM
Possible CausesExhaust gas sensor
1
2
3
4
5
6
7
8O
CONTROL SYSTEM
Possible CausesIdle switch (remaining OFF)
1
2
3
4
5O
6
7
8
OTHERS
Possible CausesFuel (poor quality)
1
2
3
4
5
6
7
8
SERVICE PROCEDURE
Service Procedure Flowchart — Symptom 14
1
CHECK 1: Check flashes of timing light for weakness. (KV109D10S0, Power transistor unit, SEF418H)
N.G.
N.G. → Check ignition signal circuit. [See page EF & EC-90.]
O.K.
2
CHECK 2: Remove spark plugs and check their ignition sparks. (Ignition coil, Spark plug, SEF428H)
3
CHECK 3: Check intake system for air leaks. (Engine, Air duct, Leak, SEF301G)
N.G.
N.G. → Repair/replace the part.
O.K.
4
PERFORM 4: Self-diagnosis Mode IV (for idle switch). (SEF285G)
N.G.
N.G. → Check the idle switch circuit. [See page EF & EC-94.]
O.K.
5
REMOVE 5: Pressure regulator — remove vacuum hose from pressure regulator, and try to drive. (SEF291G)
Improved
MEASURE 6: Fuel pressure gauge — connect vacuum hose to pressure regulator and measure fuel pressure while driving. (SEF286G)
MEASURE 6: Fuel pressure gauge — connect vacuum hose to pressure regulator and measure fuel pressure while driving. (SEF286G)
Improved → Check idle mixture ratio. [See page EF & EC-25.]
Not Improved
6
PERFORM 7: Self-diagnosis Mode III and Self-diagnosis Mode V — for air flow meter, crank angle sensor and engine temp. sensor. (SEF285G)
N.G.
N.G. → Check the malfunctioning parts and/or circuits. [See page EF & EC-84 (air flow meter), page EF & EC-82 (crank angle sensor), page EF & EC-86 (engine temp. sensor).]
N.G. → Check the malfunctioning parts and/or circuits. [See page EF & EC-84 (air flow meter), page EF & EC-82 (crank angle sensor), page EF & EC-86 (engine temp. sensor).]
O.K.
7
DISCONNECT 8: Exhaust gas sensor — disconnect exhaust gas sensor connector, and try to drive. (SEF307G)
No change
No change → Check idle mixture ratio. [See page EF & EC-25.]
Improved
Improved → Replace the sensor.
See also
EF & EC-90Trouble Diagnoses — Diagnostic Procedure 6: IGNITION SIGNAL (Code No. 21) & DETONATION SENSOR (Code No. 34)EF & EC-94Diagnostic Procedure 7 — IDLE SWITCH (Switch ON/OFF diagnosis)EF & EC-25IDLE SPEED/IGNITION TIMING/IDLE MIXTURE RATIO INSPECTIONEF & EC-84TROUBLE DIAGNOSES — Diagnostic Procedure 3 — AIR FLOW METER (Code No. 12)EF & EC-82Diagnostic Procedure 2 — CRANK ANGLE SENSOR (Code No. 11)EF & EC-86Diagnostic Procedure 4 — ENGINE TEMPERATURE SENSOR (Code No. 13)