NO.10 LOW IDLE/STALLS DURING DECELERATION [WITHOUT WU-TWC]

id0103008016c6

10

LOW IDLE/STALLS DURING DECELERATION

DESCRIPTION

• The 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 switch or related circuit malfunction (MTX)
• TR switch or related circuit malfunction (ATX)
• Improper A/C magnetic clutch operation

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Does the engine idle roughly?
Yes
Go to the symptom troubleshooting "No.8 Engine runs rough/rolling idle".
No
Go to the next step.
2
Turn off the A/C switch and 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
Inspect the following:
• Proper routing and no damage to the vacuum lines
• IAC valve is connected properly.
• No air leakage from the 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 any DTCs displayed?
Yes

DTC is displayed:

Go to the applicable DTC test.
No

No DTC is displayed:

Go to the next step.
5
Does idle speed drop or stall when the IAC valve is disconnected?
Yes
Go to the next step.
No
Inspect the following:
• Circuit from IAC valve to PCM connector terminal 2X or 2AB for open and short circuit
• IAC valve for sticking
If normal, go to the next step.
6
Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug the open end of the 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 the TP, MAF, VSS, BOO, CPP, CPP/PNP and TR PIDs.
Monitor each PID while driving the vehicle.
Are the 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 switch (MTX).

CPP/PNP PID:

Inspect the neutral switch (MTX).

TR PID:

Inspect the TR switch (ATX).
8
Verify test results.
• If normal, return to the diagnostic index to service any additional symptoms.
• If the malfunction remains, replace or reprogram the PCM.