NO.10 LOW IDLE/STALLS DURING DECELERATION [L3 Turbo]

10	LOW IDLE/STALLS DURING DECELERATION
DESCRIPTION	• Engine stops unexpectedly at beginning of deceleration or recovery from deceleration.
POSSIBLE CAUSE	• Poor fuel quality • Vacuum leakage • Improper operation of electronic throttle control system • Air leakage from intake-air system • Intake-air system restriction • EVAP control system malfunction • Improper air/fuel mixture ratio control • Erratic signal from CKP sensor • Erratic signal from CMP sensor • Accelerator position sensor or related circuit malfunction • TP sensor or related circuit malfunction • MAF sensor or related circuit malfunction • A/F sensor, HO2S or related circuit malfunction • Brake switch or related circuit malfunction • Neutral or clutch switch malfunction or related circuit malfunction • Improper A/C magnetic clutch operation • Inadequate fuel pressure (high or low pressure side) • Suction control valve malfunction (built-in high pressure fuel pump) • Relief valve malfunction (built-in delivery pipe) • Fuel leakage • Fuel line restriction • Fuel filter clogging • Incorrect fuel injection timing • High pressure fuel pump malfunction • Fuel injector malfunction • Low engine compression • Improper valve timing • EGR system malfunction • Vacuum leakage • ECT sensor or related circuit malfunction • Fuel pressure sensor or related circuit 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 [L3 Turbo].) (See AFTER SERVICE PRECAUTION [L3 Turbo].) 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.

LOW IDLE/STALLS DURING DECELERATION

DESCRIPTION

• Engine stops unexpectedly at beginning of deceleration or recovery from deceleration.

POSSIBLE CAUSE

• Poor fuel quality

• Vacuum leakage

• Improper operation of electronic throttle control system

• Air leakage from intake-air system

• Intake-air system restriction

• EVAP control system malfunction

• Improper air/fuel mixture ratio control

• Erratic signal from CKP sensor

• Erratic signal from CMP sensor

• Accelerator position sensor or related circuit malfunction

• TP sensor or related circuit malfunction

• MAF sensor or related circuit malfunction

• A/F sensor, HO2S or related circuit malfunction

• Brake switch or related circuit malfunction

• Neutral or clutch switch malfunction or related circuit malfunction

• Improper A/C magnetic clutch operation

• Inadequate fuel pressure (high or low pressure side)

• Suction control valve malfunction (built-in high pressure fuel pump)

• Relief valve malfunction (built-in delivery pipe)

• Fuel leakage

• Fuel line restriction

• Fuel filter clogging

• Incorrect fuel injection timing

• High pressure fuel pump malfunction

• Fuel injector malfunction

• Low engine compression

• Improper valve timing

• EGR system malfunction

• Vacuum leakage

• ECT sensor or related circuit malfunction

• Fuel pressure sensor or related circuit 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 [L3 Turbo].)

(See AFTER SERVICE PRECAUTION [L3 Turbo].)

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.

STEP	INSPECTION	RESULTS	ACTION
1	Does the engine idle rough?	Yes	Go to symptom troubleshooting "NO.8 ENGINE RUNS ROUGH/ROLLING IDLE". (See NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [L3 Turbo].)
No	Go to the next step.
2	Verify the following: • Fuel quality (proper octane, contamination, winter/summer blend) • Intake-air system restriction or leakage • Fuel leakage in fuel system • Vacuum leakage Are all items normal?	Yes	Go to the next step.
No	Service if necessary. Repeat Step 2.
3	Inspect CMP and CKP sensor for the following; • Installation condition (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) • Damaged trigger wheel and camshaft • Open or short circuit in the wiring harnesses Is there any malfunction detected?	Yes	Repair or replace the malfunctioning part according inspection results.
No	Go to the next step.
4	Perform the self-test function using the M-MDS. Turn the ignition switch to the ON position. Retrieve any DTCs. Is a DTC displayed?	Yes	DTC is displayed: Go to the appropriate DTC test. (See DTC TABLE [L3 Turbo].)
No	No DTC is displayed: Go to the next step.
5	Connect the M-MDS to the DLC-2. Access and monitor the following PIDs using the data monitor function. • ACSW • APP • BOO • ECT • MAF • TP • O2S11 • O2S12 • LONGFT1 • SHTFT1 • PSP (PCM terminal 1D) • CPP (PCM terminal 1S) • PNP (PCM terminal 2T) Do the PIDs indicate the correct values under trouble condition? (See PCM INSPECTION [L3 Turbo].)	Yes	Go to the next step.
No	Inspect and repair or replace suspected parts and the related harnesses. If the malfunction remains, perform the intermittent concern troubleshooting procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3 Turbo].)
6	Perform the EGR system operation inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the EGR system operate properly?	Yes	Go to the next step.
No	Inspect or replace the malfunctioning parts, according to the inspection results.
7	Perform the TP sweep inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the electronic throttle control system work properly?	Yes	Visually inspect the throttle body (damaged/scratching.) If normal, go to the next step.
No	Inspect or replace the malfunctioning parts, according to the inspection results.
8	Perform the Purge Control System Operation inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the purge solenoid valve work properly?	Yes	Go to the next step.
No	Inspect or replace the malfunctioning parts, according to the inspection results.
9	Perform the A/C Cut-off Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the A/C Cut-off Operation work properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning parts according to inspection results.
10	Access and monitor the FUEL_PRES PID. Is the FUEL_PRES PID value within the specification? (See PCM INSPECTION [L3 Turbo].)	Yes	Go to Step 14.
No	Go to the next step.
11	Is the vehicle accelerate performance normally?	Yes	Go to the next step.
No	Go to Step 14.
12	Inspect the fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [L3 Turbo].) Is the fuel pressure sensor normal?	Yes	Go to Step 14.
No	Replace the delivery pipe.
13	Replace the high pressure fuel pump Monitor FUEL_PRES PID. Is the FUEL_PRES PID value within the specified? (See PCM INSPECTION [L3 Turbo].)	Yes	Troubleshooting is completed. Go to the Step 17.
No	Go to the next step.
14	Connect the fuel pressure gauge between the fuel pump and the high pressure fuel pump. Measure the fuel pressure line of the low pressure side. (See FUEL LINE PRESSURE INSPECTION [L3 Turbo].) Is the fuel pressure within the specification?	Yes	Go to the next step.
No	Inspect for the following: • Fuel line restriction • Fuel filter clogging If normal replace the fuel pump.
15	Inspect the fuel injector for each cylinder. (See FUEL INJECTOR INSPECTION [L3 Turbo].) Are fuel injectors normal?	Yes	Go to the next step.
No	Replace the suspected fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)
16	Measure the compression pressure for each cylinder. (See COMPRESSION INSPECTION [L3 Turbo].) Are compression pressures within the specification?	Yes	Replace the injector driver module. If the problem remains, overhaul the engine.
No	Inspect for the following: • Damaged valve seat • Worn valve stem and valve guide • Worn or stuck piston ring • Worn piston, piston ring or cylinder • Improper valve timing Service if necessary.
17	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair 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

Does the engine idle rough?

Yes

Go to symptom troubleshooting "NO.8 ENGINE RUNS ROUGH/ROLLING IDLE".

(See NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [L3 Turbo].)

Go to the next step.

Verify the following:

• Fuel quality (proper octane, contamination, winter/summer blend)

• Intake-air system restriction or leakage

• Fuel leakage in fuel system

• Vacuum leakage

Are all items normal?

Yes

Go to the next step.

Service if necessary. Repeat Step 2.

Inspect CMP and CKP sensor for the following;

• Installation condition

(See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].)

(See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].)

• Damaged trigger wheel and camshaft

• Open or short circuit in the wiring harnesses

Is there any malfunction detected?

Yes

Repair or replace the malfunctioning part according inspection results.

Go to the next step.

Perform the self-test function using the M-MDS.

Turn the ignition switch to the ON position.

Retrieve any DTCs.

Is a DTC displayed?

Yes

DTC is displayed:

Go to the appropriate DTC test.

(See DTC TABLE [L3 Turbo].)

No DTC is displayed:

Go to the next step.

Connect the M-MDS to the DLC-2.

Access and monitor the following PIDs using the data monitor function.

• ACSW

• APP

• BOO

• ECT

• MAF

• TP

• O2S11

• O2S12

• LONGFT1

• SHTFT1

• PSP (PCM terminal 1D)

• CPP (PCM terminal 1S)

• PNP (PCM terminal 2T)

Do the PIDs indicate the correct values under trouble condition?

(See PCM INSPECTION [L3 Turbo].)

Yes

Go to the next step.

Inspect and repair or replace suspected parts and the related harnesses.

If the malfunction remains, perform the intermittent concern troubleshooting procedure.

(See INTERMITTENT CONCERN TROUBLESHOOTING [L3 Turbo].)

Perform the EGR system operation inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the EGR system operate properly?

Yes

Go to the next step.

Inspect or replace the malfunctioning parts, according to the inspection results.

Perform the TP sweep inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the electronic throttle control system work properly?

Yes

Visually inspect the throttle body (damaged/scratching.) If normal, go to the next step.

Inspect or replace the malfunctioning parts, according to the inspection results.

Perform the Purge Control System Operation inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the purge solenoid valve work properly?

Yes

Go to the next step.

Inspect or replace the malfunctioning parts, according to the inspection results.

Perform the A/C Cut-off Operation Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the A/C Cut-off Operation work properly?

Yes

Go to the next step.

Repair or replace the malfunctioning parts according to inspection results.

Access and monitor the FUEL_PRES PID.

Is the FUEL_PRES PID value within the specification?

(See PCM INSPECTION [L3 Turbo].)

Yes

Go to Step 14.

Go to the next step.

Is the vehicle accelerate performance normally?

Yes

Go to the next step.

Go to Step 14.

Inspect the fuel pressure sensor.

(See FUEL PRESSURE SENSOR INSPECTION [L3 Turbo].)

Is the fuel pressure sensor normal?

Yes

Go to Step 14.

Replace the delivery pipe.

Replace the high pressure fuel pump

Monitor FUEL_PRES PID.

Is the FUEL_PRES PID value within the specified?

(See PCM INSPECTION [L3 Turbo].)

Yes

Troubleshooting is completed.

Go to the Step 17.

Go to the next step.

Connect the fuel pressure gauge between the fuel pump and the high pressure fuel pump.

Measure the fuel pressure line of the low pressure side.

(See FUEL LINE PRESSURE INSPECTION [L3 Turbo].)

Is the fuel pressure within the specification?

Yes

Go to the next step.

Inspect for the following:

• Fuel line restriction

• Fuel filter clogging

If normal replace the fuel pump.

Inspect the fuel injector for each cylinder.

(See FUEL INJECTOR INSPECTION [L3 Turbo].)

Are fuel injectors normal?

Yes

Go to the next step.

Replace the suspected fuel injector.

(See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)

Measure the compression pressure for each cylinder.

(See COMPRESSION INSPECTION [L3 Turbo].)

Are compression pressures within the specification?

Yes

Replace the injector driver module.

If the problem remains, overhaul the engine.

Inspect for the following:

• Damaged valve seat

• Worn valve stem and valve guide

• Worn or stuck piston ring

• Worn piston, piston ring or cylinder

• Improper valve timing

Service if necessary.

Verify test results.

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

• If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair 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.