Knowledge Base

Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5
Home

 

< Previous   Next >

NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [SKYACTIV-G 2.0]

8

ENGINE RUNS ROUGH/ROLLING IDLE

DESCRIPTION

  • Engine speed fluctuates between specified idle speed and lower speed and, engine shakes excessively.

  • Idle speed is too slow and engine shakes excessively.

POSSIBLE CAUSE

  • Engine overheating

  • PCM DTC is stored

  • Erratic signal to PCM

    • APP sensor or related circuit malfunction

    • ECT sensor No.1 or related circuit malfunction

    • MAF sensor or related circuit malfunction

    • MAP sensor or related circuit malfunction

    • 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 A/C system

  • Improper operation of drive-by-wire control system

  • Incorrect fuel injection timing

  • Unbalanced fuel injection amount for each cylinder

  • Purge solenoid valve malfunction

  • Poor fuel quality

  • Air leakage from intake-air system

  • Vacuum leakage

  • Intake-air system restriction

  • Electrical connector disconnected

  • Fuel leakage

  • Improper engine oil viscosity

  • Erratic signal from CKP sensor

    • Loose installation

    • Damaged trigger wheel (crankshaft pulley)

    • Open or short circuit in related wiring harness

  • Erratic or no signal from CMP sensor

    • Loose installation

    • Damaged trigger wheel (intake camshaft)

    • Damaged trigger wheel (exhaust camshaft)

    • Open or short circuit in related wiring harness

  • Inadequate fuel pressure (high or low pressure side)

    • Fuel pressure sensor or related circuit malfunction

    • High pressure fuel pump malfunction

    • Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system)

    • Spill valve control solenoid valve (built-into high pressure fuel pump) malfunction

    • Relief valve (built-into high pressure fuel pump) malfunction

    • Fuel pump (low-side) body mechanical malfunction

    • Fuel filter clogged (built-into fuel pump unit)

    • Fuel injector malfunction

  • Improper intake valve timing

  • Improper exhaust valve timing

  • Improper operation of electric variable valve timing control system

    • Electric variable valve timing driver malfunction

    • Electric variable valve timing motor malfunction

    • Electric variable valve timing actuator malfunction

  • Improper operation of hydraulic variable valve timing control system

  • Low engine compression or excessive unbalance for each cylinder

  • Spark plug malfunction

  • Ignition coil malfunction

  • Exhaust system or TWC restricted

  • PCV valve malfunction

  • Injector driver (built-into PCM) malfunction

POSSIBLE CAUSE

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.

    • Highly pressurized fuel may spray out if the fuel line is cut. Due to the following dangers occurring with a fuel spray, always complete the “Fuel Line Safety Procedure” to prevent the fuel from spraying. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G 2.0].)

      • Fuel may cause irritation if it comes in contact with skin and eyes.

      • If fuel ignites and causes a fire, it may lead to serious injury or death, and damage to property and facilities.

    • Fuel is highly flammable and dangerous. Fuel line spills and leakage can cause serious injury or death, and damage to equipment. Always refer to the “Quick Release Connector Removal/Installation (fuel system)” before performing the fuel hose installation, and execute the “Fuel Leakage Inspection” after installation. (See QUICK RELEASE CONNECTOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 2.0].)

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 material.

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 on: On

  • A/C switch off: Off

APP1

%

Accelerator pedal opening angle (absolute value) input from APP sensor No.1

  • Accelerator pedal released: Approx. 15.29%

  • Accelerator pedal fully depressed: Approx. 90.98%

V

APP sensor No.1 voltage

  • Accelerator pedal released: Approx. 0.77 V

  • Accelerator pedal fully depressed: Approx. 4.55 V

APP2

%

Accelerator pedal opening angle (absolute value) input from APP sensor No.2

  • Accelerator pedal released: Approx. 7.84%

  • Accelerator pedal fully depressed: Approx. 45.49%

V

APP sensor No.2 voltage

  • Accelerator pedal released: Approx. 0.38 V

  • Accelerator pedal fully depressed: Approx. 2.27 V

ECT

°C, °F

Engine coolant temperature input from ECT sensor No.1

  • Displays ECT

V

ECT sensor No.1 voltage
    Ignition switched ON (engine off)

  • ECT is 92 °C {198 °F}: Approx. 0.65 V

    Idle (after warm up)

  • ECT is 93 °C {199 °F}: Approx. 0.64 V

    Racing (Engine speed is 2,000 rpm)

  • ECT is 92 °C {198 °F}: Approx. 0.66 V

    Racing (Engine speed is 4,000 rpm)

  • ECT is 93 °C {199 °F}: Approx. 0.64 V

FUEL_PRES

KPa , mBar , psi, in H20

Fuel pressure input from fuel pressure sensor

  • Displays fuel pressure

V

Fuel pressure sensor voltage
    Ignition switched ON (engine off)

  • Fuel pressure is approx. 3.6 MPa {37 kgf/cm2, 522 psi}: Approx. 1.01 V (ECT is 92 °C {198 °F})

    Idle (after warm up)

  • Fuel pressure is approx. 3.45 MPa {35.2 kgf/cm2, 500 psi}: Approx. 1 V (ECT is 92 °C {198 °F})

    Racing (Engine speed is 2,000 rpm)

  • Fuel pressure is approx. 3.21 MPa {32.7 kgf/cm2, 466 psi}: Approx. 0.96 V (ECT is 86 °C {187 °F})

    Racing (Engine speed is 4,000 rpm)

  • Fuel pressure is approx. 5.59 MPa {57.0 kgf/cm2, 811 psi}: Approx. 1.29 V (ECT is 84 °C {183 °F})

LOAD

%

Ratio of actual amount of intake air to the maximum air charging amount (mass volume) of cylinder

  • Idle (after warm up): Approx. 27.05% (ECT is 91 °C {196 °F})

  • Racing (engine speed is 2,000 rpm): Approx. 16.86% (ECT is 89 °C {192 °F})

  • Racing (engine speed is 4,000 rpm): Approx. 17.64% (ECT is 87 °C {189 °F})

LONGFT1

%

Fuel learning correction amount estimated based on A/F sensor signal

  • Idle (after warm up): Approx. −1.56% (ECT is 91 °C {196 °F})

  • Racing (engine speed is 2,000 rpm): 2.34% (ECT is 89 °C {192 °F})

  • Racing (engine speed is 4,000 rpm): 2.34% (ECT is 87 °C {189 °F})

MAF

g/Sec

Mass air flow input from MAF sensor

  • Displays MAF

V

MAF sensor voltage

  • Ignition switched ON (engine off) (MAF: 0.39 g/s {0.052 lb/min}): Approx. 0.72 V (ECT is 89 °C {192 °F})

  • Idle (after warm up) (MAF: 4.29 g/s {0.567 lb/min}): Approx. 1.15 V (ECT is 88 °C {190 °F})

  • Racing (engine speed is 2,000 rpm) (MAF: 4.32 g/s {0.571 lb/min}): Approx. 1.15 V (ECT is 89 °C {192 °F})

  • Racing (engine speed is 4,000 rpm) (MAF: 12.71 g/s {1.681 lb/min}): Approx. 1.66 V (ECT is 89 °C {192 °F})

MAP

KPa , mBar , psi, in H20

Manifold absolute pressure input from MAP sensor

  • Displays MAP

MAP_V

V

MAP sensor voltage

  • Ignition switched ON (engine off) (MAP:101 kPa {1.03 kgf/cm2, 14.6 psi}): Approx. 4.08 V (ECT is 89 °C {192 °F})

  • Idle (after warm up) (MAP: 31 kPa {0.32 kgf/cm2, 4.5 psi}): Approx. 1.25 V (ECT is 88 °C {190 °F})

  • Racing (engine speed is 2,000 rpm) (MAP: 32 kPa {0.33 kgf/cm2, 4.6 psi}): Approx. 1.31 V (ECT is 89 °C {192 °F})

  • Racing (engine speed is 4,000 rpm) (MAP: 49 kPa {0.50 kgf/cm2, 7.1 psi}): Approx. 2.03 V (ECT is 89 °C {192 °F})

O2S11

µA

A/F sensor current

  • Idle (after warm up): −59 µA (ECT is 92 °C {198 °F})

  • Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 3.48 mA (ECT is 92 °C {198 °F})

O2S12

V

HO2S voltage

  • Idle (after warm up): 0—1.0 V (ECT is 91 °C {196 °F})

  • Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 0 V (ECT is 92 °C {198 °F})

RPM

RPM

Engine speed

  • Displays engine speed

SHRTFT1

%

Fuel feedback correction amount estimated based on A/F sensor signal

  • Idle (after warm up): Approx. 0% (ECT is 91 °C {196 °F})

  • Racing (engine speed is 2,000 rpm): Approx. 0.78% (ECT is 89 °C {192 °F})

  • Racing (engine speed is 4,000 rpm): Approx. −21.87% (ECT is 87 °C {189 °F})

TP_REL

%

Throttle valve opening angle (relative value) with value at throttle valve fully close timing as the start point

  • Accelerator pedal released: Approx. 12.15%

  • Accelerator pedal fully depressed: Approx. 81.96%

VSS

KPH, MPH

Vehicle speed

  • Displays vehicle speed
Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION

1

 VERIFY IF MALFUNCTION INCLUDES HARD ENGINE STARTING

  • Verify the vehicle engine condition.

  • Can idling be maintained?

Yes

Go to the next step.

No

Perform the symptom troubleshooting “NO.5 ENGINE STALLS-AFTER START/AT IDLE”.

(See NO.5 ENGINE STALLS-AFTER START/AT IDLE [SKYACTIV-G 2.0].)

2

 VERIFY IF MALFUNCTION CAUSE IS OVERHEATING

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

The cause of this concern could be from the cooling system overheating.

3

 VERIFY PCM DTC

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

4

 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:

ECT PID is not as specified:

MAF PID is not as specified:

MAP, MAP_V PIDs are not as specified:

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.

5

 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 [PCM (SKYACTIV-G 2.0)].)

  • Monitor the AC_REQ PID while turning on and off the air conditioner with 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:

6

 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.

7

 INSPECT FUEL INJECTOR OPERATION

Yes

Go to the next step.

No

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

8

 INSPECT PURGE CONTROL SYSTEM OPERATION

Yes

Go to the next step.

No

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

9

 INSPECT RELATED PART CONDITION

Yes

Service if necessary.

  • Repeat this step.

No

Go to the next step.

10

 INSPECT FUEL PRESSURE (HIGH-SIDE)

Yes

Go to Step 14.

No

Lower than 3 MPa {31 kgf/cm2, 435 psi}:

Higher than 3 MPa {31 kgf/cm2, 435 psi}:

  • Go to the next step.

11

 DETERMINE IF MALFUNCTION CAUSE IS FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP

  • Is the vehicle acceleration performance normal?

Yes

Go to the next step.

No

Go to Step 13.

12

 INSPECT FUEL PRESSURE SENSOR

Yes

Replace the fuel distributor.

(See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to Step 14.

13

 INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND

  • Switch the ignition off.

  • Disconnect the high pressure fuel pump and PCM connectors.

  • Inspect for continuity between high pressure fuel pump terminal A (wiring harness-side) and body ground.

  • Is there continuity?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between high pressure fuel pump terminal A and PCM terminal 1EE.

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to ground.

If the malfunction remains:

No

Replace the high pressure fuel pump.

(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

14

 INSPECT FUEL PRESSURE (LOW-SIDE)
    Specification:

  • 425—505 kPa {4.34—5.14 kgf/cm2, 61.7—73.2 psi}

Yes

Go to the next step.

No

Inspect the following:

  • Fuel line restriction

  • Fuel filter clogged

15

 INSPECT ENGINE COMPRESSION

Yes

Go to Step 21.

No

Go to the next step.

16

 INSPECT ELECTRIC VARIABLE VALVE TIMING DRIVER

Yes

Replace the electric variable valve timing motor/driver.

(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

17

 INSPECT ELECTRIC VARIABLE VALVE TIMING MOTOR

Yes

Replace the electric variable valve timing motor/driver.

(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

18

 INSPECT ELECTRIC VARIABLE VALVE TIMING ACTUATOR

Yes

Replace the electric variable valve timing actuator.

(See ELECTRIC VARIABLE VALVE TIMING ACTUATOR, HYDRAULIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

19

 INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION

Yes

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

No

Go to the next step.

20

 INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING

Yes

Inspect for the following engine internal parts:

  • Cylinder

  • Piston ring

  • Intake valve

  • Exhaust valve

  • Such as cylinder head gasket

    • If there is any malfunction:

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

No

Adjust the valve timing to the correct timing.

21

 INSPECT IGNITION SYSTEM OPERATION

Yes

Go to the next step.

No

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

22

 INSPECT EXHAUST SYSTEM FOR RESTRICTION

  • Inspect for restriction in the exhaust system and the TWC.

  • Is there any restriction?

Yes

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

No

Go to the next step.

23

 INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR INJECTOR DRIVER (PCM INTEGRATED)

Yes

Replace the PCV valve.

(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Injector driver malfunction.

If the problem remains, overhaul the engine.

24

Verify the test results.

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

    (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.0].)

  • 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.
< Previous   Next >
 

Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5

COPYRIGHT NOTICE:
This fan site is not affiliated with Mazda, and is intended for personal, or commercial use only. The content of our web pages is for general information purposes only and is presented “as is”. We give no assurance or warranty regarding the accuracy of the contents. Readers should do their due diligence and seek the advice of an appropriately certified automotive technician before attempting any steps on this site. Original content provided by Mazda North America. The content of the manual is copyright under DMCA to: full.metal.resistor@gmail.com
LIMITATION OF LIABILITY:
We accept no responsibility for errors, inaccuracies, or omissions found on these pages. Additionally, we hereby exclude liability for any demands, claims, damages or losses of any kind with regard to any content or information provided on our web-site, including but not limited to incidental or consequential damages, direct or indirect loss, compensatory damages, loss of profits, or otherwise. By using this manual you assume full liablity for any procedures carried out on your vehicle, and are responsible for the vehicle remaining road legal and safe.