Mazda 6 2002 Workshop Manual page 307

NO.13 KNOCKING/PINGING-ACCELERATION/CRUISE
13 KNOCKING/PINGING - ACCELERATION/CRUISE
Sound is produced when air/fuel miture is ignited by something other than spark plug (e.g., hot spot in
DESCRIPTION
combustion chamber).
• Engine overheating due to cooling system malfunction
• ECT sensor malfunction
• IAT sensor malfunction
• MAF sensor malfunction
• Knock sensor malfunction
• Erratic signal from CMP sensor
• Inadequate engine compression
• Inadequate fuel pressure
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair
procedures. Read the following warnings before performing the fuel system services:
POSSIBLE CAUSE • • • • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always
• • • • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or
• • • • Disconnecting/connecting quick release connector without cleaning it may possibly cause
Diagnostic procedure
STEP
1 Connect WDS or equivalent to DLC-2.
Access ECT PID.
Verify ECT PID is less than 116° ° ° ° C {241° ° ° ° F}
during driving.
Is ECT PID less than specification?
2 Connect WDS or equivalent to DLC-2.
Access IAT, MAF and SPARKADV PIDs.
Monitor each PID.
(See F–45 PCM
Are PIDs okay?
3 Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and
KOER DTCs.
Are there any DTCs displayed?
4 Is engine compression correct?
5 Install fuel pressure gauge between fuel pipe
and fuel distributor.
Start engine and run it at idle.
Measure fuel line pressure at idle.
Is fuel line pressure correct at idle?
(See F–20 FUEL LINE PRESSURE
INSPECTION)
6 Verify test results.
• If okay, return to diagnostic inde to service any additional symptoms.
• If malfunction remains, replace PCM.
End Of Sie
F–210
TROUBLESHOOTING
keep sparks and flames away from fuel.
death 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.
(See F–17 BEFORE REPAIR
(See F–17 AFTER REPAIR
Caution
damage to fuel pipe and quick release connector. Always clean quick release connector
joint area before disconnecting/connecting, and make sure that it is free of foreign material.
INSPECTION
INSPECTION.)
PROCEDURE.)
PROCEDURE.)
RESULTS
Yes Go to net step.
No Inspect cooling system for cause of overheating.
Yes Go to net step.
No IAT PID: Inspect IAT sensor
MAF PID: Inspect MAF sensor
SPARKADV PID: Inspect CMP sensor and knock
sensor.
Yes DTC is displayed:
Go to appropriate DTC test.
No No DTC is displayed:
Go to net step.
Yes Go to net step.
No Inspect for cause.
Yes Inspect ignition timing.
No Zero or low:
Inspect for clogged fuel line.
If okay, replace fuel pump unit.
High:
Replace fuel pump unit.
A6E398018881W15
ACTION