DTC P0300 [MZI-3.7]
DTC P0300 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES
DIAGNOSTIC PROCEDURE
REPAIR PROCEDURE [MZI-
3.7]
.)
z
Are any DTC present?
No
Troubleshooting completed.
DTC P0300 Random misfire detected
DETECTION
CONDITION
z
The PCM monitors the crankshaft position sensor input signal interval time. The
PCM calculates the change of the interval time for each cylinder. If the change of
interval time exceeds the pre-programmed criteria, the PCM detects a misfire in
the corresponding cylinder. When the engine is running, the PCM counts the
number of misfires that occurred at 200 crankshaft revolutions and 1,000
crankshaft revolutions and calculates the misfire ratio for each crankshaft
revolution. If the ratio exceeds the pre-programmed criteria, the PCM determines
that a misfire, which can damage the catalytic converter or affect emission
performance, has occurred.
POSSIBLE
CAUSE
z
CMP sensor malfunction
z
CKP sensor malfunction
z
Ignition coil malfunction
z
Ignition system malfunction
z
MAF sensor contamination
z
Excess air suction in intake air system (between MAF/IAT sensor and dynamic
chamber)
z
Vacuum hoses damages or improper connection
z
Fuel pump malfunction
z
Fuel pressure regulator malfunction
z
Fuel line clogged
z
Fuel filter clogged
z
Fuel runout
z
Poor quality fuel
z
Fuel leakage in fuel line
z
Insufficient compression
z
Variable valve timing control system improper operation
z
Purge solenoid valve malfunction
z
PCV valve malfunction
z
Related connector and terminal malfunction
z
Related wiring harness malfunction
2008 Mazda CX-9 Grand Touring
2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9
Microsoft
Sunday, November 15, 2009 10:08:36 AM
Page 151
© 2005 Mitchell Repair Information Company, LLC.
