NO.10 LOW IDLE/STALLS DURING DECELERATION [AJ (3.0L Duratec)]


id0103a7801600

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
• TP sensor or related circuit malfunction
• MAF sensor or related circuit malfunction
• Brake switch or related circuit malfunction

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
• Verify following:
- Proper routing and no damage of vacuum lines
- IAC valve properly connected
- No air leakage from intake-air system
• Are all items okay?
Yes
Go to the next step.
No
Service as necessary.
Repeat Step 2.
3
• Connect WDS or equivalent to DLC-2.
• Turn key to ON (Engine OFF).
• Retrieve any DTC.
• Is "PASSED" displayed?
Yes
No DTC is displayed:
• Go to the next step.
No
DTC is displayed:
• Go to appropriate DTC test.
4
• Does idle speed drop or stall when disconnecting IAC valve?
Yes
Go to the next step.
No
Inspect following:
• Circuit from IAC valve to PCM connector terminal 54 or 83 for open or short
• Circuit from IAC valve to main relay terminal A for open or short
• IAC valve for sticking
- If okay, go to the next step.
5
• Disconnect vacuum hose between purge solenoid valve and intake manifold from purge solenoid valve side.
• Plug opening end of vacuum hose.
• Drive vehicle.
• Does engine condition improve?
Yes
Inspect EVAP control system.
No
Go to the next step.
6
• Connect WDS or equivalent to DLC-2.
• Access TP, MAF and VSS PIDs.
• Monitor each PID while driving vehicle.
• Are PIDs okay?
Yes
Intermittent concern exists.
No
TP PID:
• Inspect TP sensor.
MAF PID:
• Inspect MAF sensor.
VSS PID:
• Inspect VSS.
7
• Verify test results.
- If okay, return to diagnostic index to service any additional symptoms.
- If malfunction remains, inspect related Service Information and perform repair or diagnosis.
• If vehicle is repaired, troubleshooting completed.
• If vehicle is not repaired or additional diagnostic information is not available, replace PCM.