No.8 Engine Runs Rough/Rolling Idle: Notes

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [BP, BP WITH TC] 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 leakage from high-tension leads Purge solenoid valve malfunction Improper operation of IAC valve EGR valve malfunction Erratic or no signal from CMP sensor Low engine compression Erratic signal from CMP sensor Poor fuel quality PCV valve malfunction ACL restriction Restriction in exhaust system Disconnected electrical connectors Inadequate fuel pressure FP mechanical malfunction Fuel leakage from fuel injector Fuel injector clogged Engine overheating Vacuum leakage Variable valve timing system 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 SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION". (See BEFORE SERVICE PRECAUTION ) (See AFTER SERVICE PRECAUTION ) 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 leakage from high-tension leads
Purge solenoid valve malfunction
Improper operation of IAC valve
EGR valve malfunction
Erratic or no signal from CMP sensor
Low engine compression
Erratic signal from CMP sensor
Poor fuel quality
PCV valve malfunction
ACL restriction
Restriction in exhaust system
Disconnected electrical connectors
Inadequate fuel pressure
FP mechanical malfunction
Fuel leakage from fuel injector
Fuel injector clogged
Engine overheating
Vacuum leakage
Variable valve timing system 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 SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION".
    (See BEFORE SERVICE PRECAUTION )
    
    (See AFTER SERVICE PRECAUTION )
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.