No. 8 Engine Runs Rough/Rolling Idle: Notes

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DESCRIPTION & POSSIBLE CAUSE

8	Engine runs rough/rolling idle
DESCRIPTION	Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively. Idle speed is too slow and engine shakes excessively.
POSSIBLE CAUSE	Air leakage from intake-air system parts A/C system improper operation Spark plug malfunction Erratic signal to ignition coil Purge solenoid valve malfunction Improper operation of electronic throttle control system EGR valve malfunction Erratic or no signal from CMP sensor Low engine compression Improper valve timing Improper operation of valve timing control system Erratic signal from CKP sensor Poor fuel quality PCV valve malfunction Air cleaner restriction Restriction in exhaust system Disconnected electrical connectors Inadequate fuel pressure Fuel pump mechanical malfunction Improper load signal input Fuel line restriction or clogging Improper operation or fuel injection control Fuel leakage from fuel injector Fuel injector clogging Engine overheating Vacuum leakage Pressure regulator 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 sparks and flames away from fuel. Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or 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 BEFORE REPAIR PROCEDURE .) (See AFTER REPAIR PROCEDURE .) CAUTION: Disconnecting/connecting quick release connector without cleaning it may possibly cause 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.

Engine runs rough/rolling idle

DESCRIPTION

Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively.
Idle speed is too slow and engine shakes excessively.

POSSIBLE CAUSE

Air leakage from intake-air system parts
A/C system improper operation
Spark plug malfunction
Erratic signal to ignition coil
Purge solenoid valve malfunction
Improper operation of electronic throttle control system
EGR valve malfunction
Erratic or no signal from CMP sensor
Low engine compression
Improper valve timing
Improper operation of valve timing control system
Erratic signal from CKP sensor
Poor fuel quality
PCV valve malfunction
Air cleaner restriction
Restriction in exhaust system
Disconnected electrical connectors
Inadequate fuel pressure
Fuel pump mechanical malfunction
Improper load signal input
Fuel line restriction or clogging
Improper operation or fuel injection control
Fuel leakage from fuel injector
Fuel injector clogging
Engine overheating
Vacuum leakage
Pressure regulator 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 sparks and flames away from fuel.
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or 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 BEFORE REPAIR PROCEDURE .)
  
  (See AFTER REPAIR PROCEDURE .)

CAUTION:

Disconnecting/connecting quick release connector without cleaning it may possibly cause 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.