NO.10 LOW IDLE/STALLS DURING DECELERATION [ZY, Z6]

id0103b9801600

10

LOW IDLE/STALLS DURING DECELERATION
DESCRIPTION
•  The engine stops unexpectedly at the 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 (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 rough?
Yes
Go to symptom troubleshooting "No.8 Engine runs rough/rolling idle".
(See NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [ZY, Z6].)
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.“
(See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [ZY, Z6].)
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 WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs using WDS or equivalent.
Are there any DTCs displayed?
Yes
DTC is displayed:
Go to the appropriate DTC inspection.
(See DTC TABLE [ZY, Z6].)
No
No DTC is displayed:
Go to the next step.
5
Does the 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 terminal 2X or 2AB for open and short
•  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 opening end of vacuum hose.
Drive the vehicle.
Does the engine condition improve?
Yes
Inspect EVAP control system.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [ZY, Z6].)
No
Go to the next step.
7
Connect the WDS or equivalent to DLC-2.
Access TP, MAF, VSS, BOO, CPP, CPP/PNP and TR PIDs.
Monitor each PID while driving the vehicle.
(See PCM INSPECTION [ZY, Z6].)
Are PIDs normal?
Yes
Intermittent concern exists.
(See INTERMITTENT CONCERN TROUBLESHOOTING [ZY, Z6].)
No
TP PID:
Inspect the TP sensor.
(See THROTTLE POSITION (TP) SENSOR INSPECTION [ZY, Z6].)
MAF PID:
Inspect the MAF sensor.
(See MASS AIR FLOW (MAF) SENSOR INSPECTION [ZY, Z6].)
VSS PID:
Inspect the VSS.
(See DTC TABLE [ZY, Z6].)
BOO PID:
Inspect the brake switch.
(See BRAKE SWITCH INSPECTION.)
CPP PID:
Inspect the clutch pedal position switch (MTX).
(See CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [ZY, Z6].)
CPP/PNP PID:
Inspect the neutral switch (MTX).
(See NEUTRAL SWITCH INSPECTION [ZY, Z6].)
TR PID:
Inspect the TR switch (ATX).
(See TRANSAXLE RANGE (TR) SWITCH INSPECTION.)
8
Verify test results.
•  If normal, return to diagnostic index to service any additional symptoms.
•  If malfunction remains, inspect related Service information perform repair or diagnosis.
―  If vehicle repaired, troubleshooting completed.
―  If vehicle not repaired or additional diagnostic information not available, replace the PCM.