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Home >> Mazda >> 2014 >> 3 SV, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting - Engine Controls >> No. 9 Fast Idle/Runs On >> Notes
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No. 9 Fast Idle/Runs On: Notes

NO. 9 FAST IDLE/RUNS ON DESCRIPTION AND POSSIBLE CAUSES (SKYACTIV-G 2.0, SKYACTIV-G 2.5)

9  FAST IDLE/RUNS ON 
DESCRIPTION 
  • Engine speed continues at fast idle after warm-up.
  • Engine runs after ignition is switched off.
POSSIBLE CAUSE 
  • Cooling system malfunction
  • PCM DTC is stored
  • Accelerator pedal stuck depressed
  • Erratic signal to PCM
    • APP sensor or related circuit malfunction
    • Neutral switch or related circuit malfunction (MTX)
    • Communication error between TCM and PCM (ATX)
    • A/F sensor or related circuit malfunction
    • HO2S or related circuit malfunction
    • Improper air/fuel mixture ratio control operation
  • Improper load signal input
    • Improper A/C request signal
  • Improper operation of drive-by-wire control system
  • Throttle body malfunction
  • Fuel injector malfunction
  • Spill valve control solenoid valve (built-into high pressure fuel pump) malfunction
  • Improper operation of cruise control system
  • Air leakage from intake-air system
  • Injector driver (built-into PCM) malfunction
    WARNING: The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services:
    • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
    • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual. (See BEFORE SERVICE PRECAUTION .) (See AFTER SERVICE PRECAUTION .)
    CAUTION:
    • Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign matter.
CAUTION:
  • Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.
RELATED PIDS

Item (definition) Unit/Condition Definition Condition/Specification (Reference)
AC_REQ Off/On A/C switch status received by PCM via CAN
  • A/C switch off: Off
  • A/C switch on: On
APP1 % Accelerator pedal opening angle (absolute value) input from APP sensor No. 1
  • Accelerator pedal released: Approx. 15%
  • Accelerator pedal fully depressed: Approx. 82%
V APP sensor No. 1 voltage
  • Accelerator pedal released: Approx. 0.75 V
  • Accelerator pedal fully depressed: Approx. 4.1 V
APP2 % Accelerator pedal opening angle (absolute value) input from APP sensor No. 2
  • Accelerator pedal released: Approx. 7.45%
  • Accelerator pedal fully depressed: Approx. 41%
V APP sensor No. 2 voltage
  • Accelerator pedal released: Approx. 0.38 V
  • Accelerator pedal fully depressed: Approx. 2.05 V
CPP/PNP (MTX) Off/On Shift lever position
  • Other than neutral: Off
  • Neutral: On
ECT °C, °F Engine coolant temperature
  • Displays ECT
V ECT sensor No. 1 voltage
  • ECT is 20 °C {68 °F}: Approx. 3.10 V
  • ECT is 40 °C {104 °F}: Approx. 2.16 V
  • ECT is 60 °C {140 °F}: Approx. 1.40 V
  • ECT is 80 °C {176 °F}: Approx. 0.87 V
  • ECT is 100 °C {212 °F}: Approx. 0.54 V
FUEL_PRES KPa {MPa}, mBar {Bar}, psi, in H20 Fuel pressure
  • Displays fuel pressure
V Fuel pressure sensor voltage
  • Fuel pressure is 3.0 MPa {31 kgf/cm2 , 435 psi}: Approx. 0.92 V
  • Fuel pressure is 4.8 MPa {49 kgf/cm2 , 696 psi}: Approx. 1.17 V
LOAD % Ratio of actual amount of intake air to the maximum air charging amount (mass volume) of cylinder
  • Idle (after warm up): Approx. 17.64%
  • Racing (engine speed is 2, 000 rpm): Approx. 14.51%
  • Racing (engine speed is 4, 000 rpm): Approx. 21.17%
LONGFT1 % Fuel learning correction amount estimated based on A/F sensor signal
  • Idle (after warm up): Approx. -2.34%
  • Racing (engine speed is 2, 000 rpm): Approx. -0.78%
  • Racing (engine speed is 4, 000 rpm): Approx. -0.78%
O2S11 μA A/F sensor current
  • Idle (after warm up): Approx. -39 μA
  • Deceleration fuel cut (accelerator pedal released from engine speed of 4, 000 rpm or more): Approx. 3.84 mA
O2S12 V HO2S voltage
  • Idle (after warm up): 0-1.0 V
  • Deceleration fuel cut (accelerator pedal released from engine speed of 4, 000 rpm or more): Approx. 0 V
RPM RPM Engine speed
  • Displays engine speed
SHRTFT1 % Fuel feedback correction amount estimated based on A/F sensor signal
  • Idle (after warm up): Approx. 1.56%
  • Racing (engine speed is 2, 000 rpm): Approx. -3.12%
  • Racing (engine speed is 4, 000 rpm): Approx. -8.59%
TP_REL % Throttle valve opening angle (relative value) with value at throttle valve fully open timing as the start point
  • Accelerator pedal released: Approx. 12%
  • Accelerator pedal fully depressed: Approx. 82%
VSS KPH, MPH Vehicle speed
  • Displays vehicle speed
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