Mazda MX-6 1998, Workshop Manual

Page: 353 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
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.
• IAC valve properly connected.
• No air leak from intake air system.
Are all items okay?
Yes Go to next step.
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 No DTCs displayed.
Go to next step.
4 Does idle speed drop or stall when
disconnecting IAC valve?
Yes Go to next step.
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.
Plug opening end of vacuum hose.
Drive vehicle.
Does engine condition improve?
Yes Check evaporative emission control system.
No Go to next step.
6 Connect NGS tester to DLC.
Access TP V PID, MAF PID, TCC PID, BOO
P ID and CPP/PNP PID.
Monitor each PIDs while driving vehicle.
• TP V PID
c r 01-40B THROTTLE POSITION
SENSOR INSPECTION [KL]
• MAF PID
c r 0 1 -40B MASS AIR FLOW SENSOR
INSPECTION [KL]
• BOO PID
c r 04-11 BRAKE SWITCH INSPECTION
• CPP/PNP PID
c r 0 1 -40B NEUTRAL SWITCH
INSPECTION [KL]
c r 01-40B CLUTCH SWITCH
INSPECTION [KL]
• TCC PID
c r
05-17B ELECTRICAL SYSTEM
COMPONENT [GF4A-EL], Torque
Converter Clutch Inspection
Are
PIDs
okay?
Yes Go to flow chart 27 for “Intermittent concerns".
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.
01-01B -147