Chery QQ6 Service Manual download pdf (Page 21)

11. Spark Plug

The operating conditions of spark plug is extremely inclement, it is exposed to high pressure,

high temperature and impact as well as strong corrosion from combustion product; therefore, it is a

wearing part.

11.1 Outline drawing

11.2 Thermal performance

The spark plug must maintain a proper temperature to keep good working order. Practically,

when insulator skirt of the spark plug maintains a temperature of 500-700 , the oil drop that falls ℃

on the insulator can be burnt away immediately without carbon deposit formed. This temperature

is called “self cleaning temperature of spark plug”. With a temperature below this scope, the spark

plug is liable to carbon deposit and electric leakage, thus causing ignition failure; with a temperature

above this scope, when the mixed air is contacting with the red-hot insulator, pre-ignition may occur

to produce knock, even it may burn in intake stroke and cause backfire.

11.3 Potential failures due to fall of ignition performance of spark plug

Starting difficulties, unsteady speed, chatter of engine, black smoke out of exhaust pipe, high

fuel consumption and poor power.

11.4 Judge if the vehicle status matches with the spark plug type through color of spark plug

Yellow, brown yellow normal indicates that the combustion status of mixed air is normal

Black with carbon deposit carbon deposit check if the spark plug type matches and then

replace with the spark plug with lower heat value (slow heat radiation).

Black with blot soot clean if the injector nozzle is dirty

Dilute if the mixture ratio of oil gas is too big.

Check ignition coil etc. if the high voltage is poor.

Black with oil stain combustion of engine oil check sealing status of the seal ring and if

Mono-pole Triple-pole

Covered with rivet

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Chery QQ6 Service Manual Page 21