Mazda Mazda6 Workshop Manual Supplement page 342

NO.10 LOW IDLE/STALLS DURING DECELERATION
10 LOW IDLE/STALLS DURING DECELERATION
• Engine stops unexpectedly at beginning of deceleration or recovery from deceleration.
DESCRIPTION
• Intake-air system restriction or clogging
• Poor fuel quality
• A/C system improper operation
• Inadequate fuel pressure
• Suction control valve malfunction (built-in supply pump)
• Fuel pressure limiter malfunction (built-in common rail)
• Fuel leakage
• Fuel line restriction or clogging
• Fuel filter restriction or clogging
• Incorrect fuel injection timing
• Incorrect idle speed
• Erratic signal from CKP sensor
• Erratic signal from CMP sensor
• Supply pump malfunction
• Fuel injector malfunction
• Low engine compression
• Improper valve timing
• Glow system malfunction
POSSIBLE
• EGR system malfunction
CAUSE
• MAF/IAT sensor or related circuit malfunction
• ECT sensor or related circuit malfunction
• Fuel pressure sensor or related circuit malfunction
• Neutral switch malfunction or related circuit malfunction
• Accelerator position sensor or related circuit malfunction
• Idle switch or related circuit malfunction
• Incorrect adjustment accelerator position sensor and/or idle switch
• IDM or related circuit malfunction
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair
procedures. Read the following warnings before performing the fuel system services:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death
Diagnostic Procedure
STEP
1 Does engine idle rough?
2 Inspect for following:
• Fuel line/fuel filter clogging or restriction
• Intake-air system restriction or clogging
• Fuel quality (e.g.: include water
contamination, winter/summer blend)
Are all items okay?
3 Perform self-test function using WDS or
equivalent.
Turn engine switch to ON.
Retrieve any DTC.
Is DTC displayed?
4 Inspect idle speed.
(See F2–34 IDLE SPEED
Is idle speed correct?
F2–190
TROUBLESHOOTING
sparks and flames away from fuel.
and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE
REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.
INSPECTION
INSPECTION)
RESULTS
Yes Go to symptom troubleshooting "NO.8 ENGINE RUNS
ROUGH/ROLLING IDLE".
No Go to next step.
Yes Go to next step.
No Service as necessary.
Repeat Step 2.
Yes DTC is displayed:
Go to appropriate DTC test.
Communication error message is displayed:
Inspect for following:
• Open circuit between PCM control relay and PCM
terminal 53 or 79
• Open circuit PCM control relay and PCM terminal
69
• PCM control relay stuck open
• Open or poor GND circuit (PCM terminal 65, 85,
103 or 104)
• Poor connection vehicle body GND
No No DTC is displayed:
Go to next step.
Yes Go to next step.
No Repair or replace malfunctioning part according to idle
speed inspection results.
A6E408018881212
ACTION