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

BME010300103248

10

LOW IDLE/STALLS DURING DECELERATION

DESCRIPTION

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

POSSIBLE CAUSE

• Vacuum leakage
• IAC valve malfunction
• Air leakage from intake-air system
• Improper air/fuel mixture ratio control
• Evaporative emission control system malfunction
• TP sensor misadjustment
• TP sensor or related circuit malfunction
• MAF sensor or related circuit malfunction
• Brake switch or related circuit malfunction
• Neutral/clutch pedal position switch or related circuit malfunction
• Improper A/C magnetic clutch operation

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
• Does engine idle rough?
Yes
Go to symptom troubleshooting "No.8 Engine runs rough/rolling idle".
No
Go to the next step.
2
Turn off the A/C switch and the fan switch.
Does the A/C magnetic clutch engage?
Yes
Go to symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously."
No
Go to the next step.
3
Verify the following:
• Proper routing and no damage of vacuum lines
• IAC valve is connected properly.
• No air leakage from intake-air system
Are all items normal?
Yes
Go to the next step.
No
Service if necessary.
Repeat Step 3.
4
Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes

DTC is displayed:

Go to the applicable DTC inspection.
No

No DTC is displayed:

Go to the next step.
5
Does idle speed drop or stall when disconnecting the IAC valve?
Yes
Go to the next step.
No
Inspect the following:
• Circuit from IAC valve to PCM connector terminal 4G or 4J for open and short
• IAC valve for sticking
If normal, go to the next step.
6
Disconnect vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug opening end of vacuum hose.
Drive the vehicle.
Does the engine condition improve?
Yes
Inspect the evaporative emission control system.
No
Go to the next step.
7
Connect the WDS or equivalent to the DLC-2.
Access TP, MAF, VSS, BOO, CPP and CPP/PNP PIDs.
Monitor each PID while driving the vehicle.
Are PIDs normal?
Yes
Intermittent concern exists.
No

TP PID: Inspect the TP sensor.

MAF PID: Inspect the MAF sensor.

VSS PID: Inspect the VSS.

BOO PID: Inspect the brake switch.

CPP PID: Inspect the clutch pedal position switch.

CPP/PNP PID: Inspect the neutral switch.

8
Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM.