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2014 - Mazda6 - Engine

NO.9 FAST IDLE/RUNS ON [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 [SKYACTIV-G 2.5].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 2.5].)

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:

Related PIDs

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)

AC_REQ

Off/On

A/C request signal

  • A/C switch off: Off

  • A/C switch on: On

APP1

%

APP sensor No.1

  • Accelerator pedal released: Approx. 15%

  • Accelerator pedal depressed: Approx. 82%

V

  • Accelerator pedal released: Approx. 0.75 V

  • Accelerator pedal depressed: Approx. 4.1 V

APP2

%

APP sensor No.2

  • Accelerator pedal released: Approx. 7.45%

  • Accelerator pedal depressed: Approx. 41%

V

  • Accelerator pedal released: Approx. 0.38 V

  • Accelerator pedal 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 (No.1)

  • Displays ECT

V

  • 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 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

%

Engine load

  • 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

%

Long term fuel trim

  • 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

  • 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

  • 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

%

Short term fuel trim

  • 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 position signal (relative value)

  • Accelerator pedal released: Approx. 12%

  • Accelerator pedal depressed: Approx. 82%

VSS

KPH, MPH

Vehicle speed

  • Displays vehicle speed

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION

1

 INSPECT COOLING SYSTEM FOR MALFUNCTION

Yes

Go to the next step.

No

ECT PID value is higher than 112 °C {234 °F}:

ECT PID value is less than 82 °C {180 °F}:

2

 VERIFY PCM DTC

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [SKYACTIV-G 2.5].)

No

Go to the next step.

3

 VERIFY CURRENT INPUT SIGNAL STATUS

CAUTION:

  • While performing this step, always operate the vehicle in a safe and lawful manner.

  • When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.

Yes

Go to the next step.

No

APP1, APP2 PIDs are not as specified:

CPP/PNP PID is not as specified: (MTX)

O2S11, SHRTFT1, LONGFT1 PIDs are not as specified:

O2S12 PID is not as specified:

Repair or replace the malfunctioning part according to the inspection results.

  • If the malfunction remains:

    • Inspect communication error between TCM and PCM. (ATX)

      • Repair or replace the malfunctioning part according to the inspection results if necessary.

    • Perform the “INTERMITTENT CONCERN TROUBLESHOOTING” procedure.

      (See INTERMITTENT CONCERN TROUBLESHOOTING [SKYACTIV-G 2.5].)

4

 DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER

  • Access the AC_REQ PID using the M-MDS.

    (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

  • Monitor the AC_REQ PID while turning on and off the air conditioner using the switch on the control panel.

  • Does the AC_REQ PID value change from on to off according to switch control panel?

Yes

Go to the next step.

No

If the AC_REQ PID is always ON:

If the AC_REQ PID is always OFF:

5

 INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION

Yes

Visually inspect the throttle body (damage/scratching).

  • If there is any malfunction:

    • Repair or replace the malfunctioning part according to the inspection results.

  • If there is no malfunction:

    • Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

6

 INSPECT FUEL INJECTOR OPERATION

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

7

 INSPECT HIGH PRESSURE FUEL PUMP

Yes

Replace the high pressure fuel pump.

(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

No

Go to the next step.

8

 INSPECT CRUISE CONTROL SYSTEM

  • Inspect the operation of cruise control system.

  • Does the cruise control system work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

9

 INSPECT INTAKE-AIR SYSTEM FOR AIR LEAKAGE

  • Inspect for leakage in intake-air system.

  • Is there any leakage?

Yes

Repair or replace the malfunctioning part according to the inspection results.

No

Injector driver malfunction.

If the problem remains, overhaul the engine.

10

Verify the test results.

  • If normal, return to the diagnostic index to service any additional symptoms.

    (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.5].)

  • If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.

    • If the vehicle is repaired, troubleshooting is completed.

    • If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.



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