LEMON Manuals: Even more car manuals for everyone
Home >> Mazda >> 2017 >> CX-5 Grand Select, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 145 (On-Board Diagnostic - Engine Control (2 Of 5)) >> DTC P0300; Pcm Random Misfire Detected >> Details On DTCs

Details On DTCs

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
DETECTION CONDITION AND POSSIBLE CAUSE

DESCRIPTION Random misfire detected
DETECTION CONDITION Determination conditions
  • Any one of the following conditions is met:
    • The misfire rate for every 200 rotations of the crankshaft exceeds the specified value (misfire which may damage catalytic converter).
      • The misfire rate for every 1, 000 rotations of the crankshaft exceeds the specified value (misfire going against emission regulations).
Preconditions
  • Battery voltage: 9-18 V(1)
  • Engine speed: 500-6, 700 rpm(1)(U.S.A. and CANADA)
  • Engine speed: 500-4, 500 rpm(1)(except U.S.A. and CANADA)
  • Engine coolant temperature: -10 °C {14 °F} or more(1) (U.S.A. and CANADA)
  • Engine coolant temperature: 20 °C {68 °F} or more(1) (except U.S.A. and CANADA)
  • Not cranking (U.S.A. and CANADA)
  • Not stalling (U.S.A. and CANADA)
  • Fuel-cut control not implemented
  • Crankshaft installation tolerance learning completed
  • Engine condition is stabilized (not directly after gear change)
Malfunction determination period
  • 200 rotations of crankshaft (misfire which may damage catalytic converter)
  • 1, 000 rotations of crankshaft (misfire going against emission regulations)
Drive cycle
  • 2
Self test type
  • CMDTC self test
Sensor used
  • CKP sensor
  • MAF sensor
  • MAP sensor
FAIL-SAFE FUNCTION
  • Limits intake air amount
  • Implement fuel-cut control (if the catalytic converter may be damaged, perform fuel-cut on cylinder misfiring the most).
VEHICLE STATUS WHEN DTCs ARE OUTPUT
  • Misfiring which may damage catalytic converter (number of drive cycles: 1):
    • Check engine light flashes and pending code is recorded
  • Drive cycle directly after above drive cycle (number of drive cycles: 2):
    • Malfunction determined: check engine light is illuminated
      • Normal is determined: Pending code cleared
  • Rough idling, poor acceleration, stalling
POSSIBLE CAUSE
  • Improper operation of ignition system
    • Spark plug malfunction
    • Ignition coil related wiring harness or connector malfunction
      • Ignition coil malfunction
  • Fuel injector malfunction
    • Improper operation of fuel injector
      • Fuel injector related wiring harness malfunction
  • Erratic signal to PCM
    • CKP sensor signal malfunction
    • ECT sensor No. 1 signal malfunction
    • MAF sensor signal malfunction
    • MAP sensor signal malfunction
    • IAT sensor No. 1 signal malfunction
    • APP sensor signal malfunction
    • TP sensor signal malfunction
    • VSS signal malfunction
    • Related connector or terminals malfunction
      • Related wiring harness malfunction
  • Poor drive belt assembly or adhesion of oil
  • Drive belt auto tensioner malfunction
  • Air leakage from intake air system (between intake manifold and cylinder head)
  • Engine malfunction
    • Insufficient engine compression
      • Engine coolant leakage to combustion chamber
  • PCM malfunction
(1) Value can be verified by displaying PIDs using M-MDS
scientia non olet · About LEMON Manuals