Mazda MX-5 Miata / Grand Touring. Manual - part 133

1. If there is carbon adhering to the spark plug, perform no-load racing at 4,000 rpm for 2 min, 2 times .  

VISUAL INSPECTION 

1. Inspect the following items: 



If any of the following malfunction are indicated, replace the spark plug. 



Insulator breakage  



Worn electrode  



Damaged gasket  



Badly burned insulator (sparking side) 

there is any malfunction such as rough idling or start difficulty due to 
carbon adhesion causing plug fouling, burn off the carbon by 
performing no-load racing of the engine.  



When performing the no-load racing, apply the side brake and foot 
brake, move the shift lever to neutral (MT), or the selector lever to P 
position (AT) to prevent an accident and serious injury.  



To avoid possible damage to the spark plug tip, do not use a wire 
brush for cleaning.  

NOTE:



To avoid possible damage to the tip, use gasoline to clean the spark plugs 
after removing dirt.  



If the accelerator pedal is depressed continuously for a specified time, the 
engine speed may decrease to the idle speed. This is due to the fuel cut 
control operation, which prevents overheating, and it does not indicate a 
malfunction.  



Do not perform no-load racing at high engine speed continuously for 10s 
or more.  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Ignition System - MX-5 Miata

  

Fig. 4: Inspecting Spark Plug 
Courtesy of MAZDA MOTORS CORP. 

RESISTANCE INSPECTION 

1. Measure the resistance of the spark plug using a tester as shown in Fig. 5 . 



If not within the specification, replace the spark plug.  

Spark plug resistance [25°C {77°F}]  

3.0-7.5 kilohms  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Ignition System - MX-5 Miata

  

Fig. 5: Measuring Resistance Of Spark Plug 
Courtesy of MAZDA MOTORS CORP. 

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Ignition System - MX-5 Miata

  

2008 ENGINE PERFORMANCE

Intake Air System - MX-5 Miata 

INTAKE AIR SYSTEM LOCATION INDEX [LF] 

Fig. 1: Identifying Intake Air System Components 
Courtesy of MAZDA MOTORS CORP. 

Intake Air System Location Index [LF] 

1

Intake-air system

2

Air cleaner

3

Fresh-air duct

4

Variable intake air solenoid valve

5

Variable intake air shutter valve actuator

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE PERFORMANCE Intake Air System - MX-5 Miata

  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE PERFORMANCE Intake Air System - MX-5 Miata