Mazda MX-6 1998, Workshop Manual

Page: 170 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
9 LOW IDLE/STALLS DURING DECELERATION
DESCRIPTION
Engine stops unexpectedly at beginning of deceleration or recovery from deceleration
POSSIBLE
CAUSE
• Vacuum leaks
• IAC valve malfunction
• Air leak from intake air system
• Throttle position sensor or related circuit malfunction
• Mass air flow sensor or related circuit malfunction
• Brake switch or related circuit malfunction
• Clutch position and/or neutral switch or related circuit malfunction
STEP INSPECTION
ACTION
1
Does engine idle rough? Yes
Go to flow chart 7 for “ENGINE RUNS ROUGH/ROLLING
IDLE”.
No Go to next step.
2
Check following:
• Proper routing and no damage of vacuum
lines.
Yes Go to next step.
• IAC valve properly connected.
• No air leak from intake air system.
Are all items okay?
No Service as necessary. Repeat step 2.
3 Retrieve and record any continuous memory,
KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes Go to appropriate DTC test.
No
Go to next step.
4 Does idle speed drop or stall when Yes Go to next step.
disconnecting IAC valve?
No Check following:
• Circuit from idle air control valve to PCM for open and
short.
• Idle air control valve for sticking.
If okay, go to next step.
5
Disconnect vacuum hose between purge
solenoid valve and intake manifold from
solenoid valve side.
Yes Check evaporative emission control system.
Plug opening end of vacuum hose.
Drive vehicle.
Does engine condition improve?
No
Go to next step.
6
Connect NGS tester to data DLC.
Access TP V PID, MAF PID, TCCA PID, BOO
PID and CPP/PNP PID.
Monitor each PID while driving vehicle.
• TP V PID.
0 1 -4 0 A THROTTLE POSITION
SENSOR INSPECTION [FS]
• MAF PID.
ip- 01—40A MASS AIR FLOW SENSOR
Yes Go to flow chart 27 for “Intermittent concerns”.
INSPECTION [FS]
• BOO PID.
D- 04-11 BRAKE SWITCH INSPECTION
• CPP/PNP PID.
a- 01—40A NEUTRAL SWITCH
INSPECTION [FS]
tr 0 1 -4 0 A CLUTCH SWITCH
INSPECTION [FS]
• TCC PID.
tr 0 5 -1 7A ELECTRICAL SYSTEM
COMPONENT [LA4A-EL], Torque
Converter Clutch Inspection
Are PIDs okay?
No TP V PID: Check for TP sensor.
MAF PID: Check for mass air flow sensor.
TCC PID: Check TCC solenoid valve.
BOO PID: Check brake on/off switch.
CPP/PNP PID: Check clutch and neutral switches.
7 Verify test results. If okay, return to diagnostic index to service any additional symptoms.
01-01A-142