NO.5 STUMBLE [MZ-CD 1.6]

5	Stumble
DESCRIPTION	• Engine stumbling. • Engine stumbling and glow indicator light is flashing.
POSSIBLE CAUSE	• PCM DTC is detected. • Fuel tank fuel level low. • Air cleaner element restriction • Loose vacuum line(s)/vacuum connections • Loose intake-air system hose(s)/hose connections • Loose intake-air system tube(s)/tube connections • Coolant leakage • Oil leakage • Fuel leakage • Visibly damaged or worn parts • Loose or missing nuts or bolts • Incorrect or contaminated fuel in fuel tank • Electrical connector, wiring harness or component damaged • Erratic signal to PCM ― APP sensor signal malfunction • Fuel injector malfunction • Fuel pressure sensor malfunction • Supply pump malfunction • PCM malfunction

Stumble

DESCRIPTION

• Engine stumbling.

• Engine stumbling and glow indicator light is flashing.

POSSIBLE CAUSE

• PCM DTC is detected.

• Fuel tank fuel level low.

• Air cleaner element restriction

• Loose vacuum line(s)/vacuum connections

• Loose intake-air system hose(s)/hose connections

• Loose intake-air system tube(s)/tube connections

• Coolant leakage

• Oil leakage

• Fuel leakage

• Visibly damaged or worn parts

• Loose or missing nuts or bolts

• Incorrect or contaminated fuel in fuel tank

• Electrical connector, wiring harness or component damaged

• Erratic signal to PCM

― APP sensor signal malfunction

• Fuel injector malfunction

• Fuel pressure sensor malfunction

• Supply pump malfunction

• PCM malfunction

STEP	INSPECTION	RESULTS	ACTION
1	VERIFY PCM DTC • Perform the PCM DTC inspection using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZ-CD 1.6].) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [MZ-CD 1.6].)
No	Go to the next step.
2	VISUALLY INSPECT RELATED PART CONDITION • Visually inspect the following: Mechanical: ― Fuel level ― Air cleaner element ― Vacuum line(s)/vacuum connections ― Hose(s)/hose connections ― Tube(s)/tube connections ― Fuel system leaks (Fuel filter, fuel supply line(s), fuel return line(s), high-pressure fuel supply line(s), fuel injectors, fuel rail, supply pump) ― Contaminated fuel Electrical: ― Fuse(s) ― Relay(s) ― Loose or corroded connector(s) (PCM, sensor(s), switch(es)) ― Damaged or worn PCM, switch(es) and/or sensor(s) ― Wiring harness • Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 2.
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. • Access the following PIDs using the M-MDS: (See PCM INSPECTION [MZ-CD 1.6].) ― APP1 ― APP2 • Monitor the each PID while driving the vehicle. • Are all PIDs normal?	Yes	Go to the next step.
No	If the APP1 and/or APP2 PIDs are not specified: • Inspect the APP sensor and related wiring harness. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZ-CD 1.6].) Repair or replace malfunctioning part.
4	INSPECT FUEL INJECTOR • Inspect the fuel injector for each cylinder. (See FUEL INJECTOR INSPECTION [MZ-CD 1.6].) • Are fuel injectors normal?	Yes	Go to the next step.
No	Replace the suspected fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION [MZ-CD 1.6].)
5	DETERMINE IF MALFUNCTION CAUSE IS SUPPLY PUMP/FUEL METERING VALVE OR OTHER 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. • Access the following PIDs using the M-MDS: (See PCM INSPECTION [MZ-CD 1.6].) ― FRP ― FRP_DSD ― FUEL_V_DSD • Monitor the each PID while driving the vehicle. • Are all PIDs normal?	Yes	Replace the fuel. (Poor fuel quality (e.g.: include water contamination, winter/summer blend)) • Flush the fuel line as necessary.
No	Inspect the fuel pressure sensor and related wiring harness. (See FUEL PRESSURE SENSOR INSPECTION [MZ-CD 1.6].) • If there is malfunction, repair or replace malfunctioning part. If the ECT PID is not specified: • If there is no malfunction, replace the supply pump. (See SUPPLY PUMP REMOVAL/INSTALLATION [MZ-CD 1.6].)
6	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZ-CD 1.6].) • If the malfunction remains, inspect the related Service Information and perform the 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.

STEP

INSPECTION

RESULTS

ACTION

VERIFY PCM DTC

• Perform the PCM DTC inspection using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [MZ-CD 1.6].)

• Are any DTCs present?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [MZ-CD 1.6].)

Go to the next step.

VISUALLY INSPECT RELATED PART CONDITION

• Visually inspect the following:

Mechanical:

― Fuel level

― Air cleaner element

― Vacuum line(s)/vacuum connections

― Hose(s)/hose connections

― Tube(s)/tube connections

― Fuel system leaks (Fuel filter, fuel supply line(s), fuel return line(s), high-pressure fuel supply line(s), fuel injectors, fuel rail, supply pump)

― Contaminated fuel

Electrical:

― Fuse(s)

― Relay(s)

― Loose or corroded connector(s) (PCM, sensor(s), switch(es))

― Damaged or worn PCM, switch(es) and/or sensor(s)

― Wiring harness

• Is there any malfunction?

Yes

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

Repeat Step 2.

Go to the next step.

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.

• Access the following PIDs using the M-MDS:

(See PCM INSPECTION [MZ-CD 1.6].)

― APP1

― APP2

• Monitor the each PID while driving the vehicle.

• Are all PIDs normal?

Yes

Go to the next step.

If the APP1 and/or APP2 PIDs are not specified:

• Inspect the APP sensor and related wiring harness.

(See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZ-CD 1.6].)

Repair or replace malfunctioning part.

INSPECT FUEL INJECTOR

• Inspect the fuel injector for each cylinder.

(See FUEL INJECTOR INSPECTION [MZ-CD 1.6].)

• Are fuel injectors normal?

Yes

Go to the next step.

Replace the suspected fuel injector.

(See FUEL INJECTOR REMOVAL/INSTALLATION [MZ-CD 1.6].)

DETERMINE IF MALFUNCTION CAUSE IS SUPPLY PUMP/FUEL METERING VALVE OR OTHER

Caution

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

• Access the following PIDs using the M-MDS:

(See PCM INSPECTION [MZ-CD 1.6].)

― FRP

― FRP_DSD

― FUEL_V_DSD

• Monitor the each PID while driving the vehicle.

• Are all PIDs normal?

Yes

Replace the fuel.

(Poor fuel quality (e.g.: include water contamination, winter/summer blend))

• Flush the fuel line as necessary.

Inspect the fuel pressure sensor and related wiring harness.

(See FUEL PRESSURE SENSOR INSPECTION [MZ-CD 1.6].)

• If there is malfunction, repair or replace malfunctioning part.

If the ECT PID is not specified:

• If there is no malfunction, replace the supply pump.

(See SUPPLY PUMP REMOVAL/INSTALLATION [MZ-CD 1.6].)

Verify test results.

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

(See SYMPTOM DIAGNOSTIC INDEX [MZ-CD 1.6].)

• If the malfunction remains, inspect the related Service Information and perform the 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.