If 1 or 2 pieces of spark plugs don't sparkle, not only the gasoline consumption increases, but also increases exhaustion of harmful gas (CO, NOx, HC).
Causes:
A. The gap betiveen electrodes is not proper. If too small, it will limit the area on which the spark will contact with mixed gas, and the spark is weak to ignite mixed gas. If too big, the voltage from the coil for ignition will be not enough, it can not create spark.
B. Gasoline or mobile oil adhered on the surface of electrode. This circumstance appears due to not correct controlling gasoline or mobile oil entered into cylinder via interval between the surfaces of cylinder and piston. These gasoline, mobile oil or water can result in short circuit.
C. Insulator of spark plug broke, The high voltage electrical current will leak.
D. Carbonation on electrode. Serious carbonation will lead to short circuit and in result there is no spark.
E. Electrodes broke. The reason is galvanic corrosion or chemical corrosion.
F. Super-low insulating resistance of spark plugs. It will decrease the ignition voltage and weaken the spark. As a result of it spark plugs lose their ignition ability.
G.. H.V cable appears short circuit.
H. Pt-contactor burnt up. As a result of it whole spark plugs will not sparkle.
I. Elastic force of spring for Pt-contactor is too weak. As a result of it the closing time of the contactor is too short, even no closing.
J. Insulating puncture of capacitor. In result it loses its efficiency.
K. Ignition coil broke.