|Spark plug won't last
My Waja's spark plug does not last. The most is 7,000km to 8,000km, then the
car starts to jerk at 90km/h to 110km/h. The mileage is now 80,000km. What
causes this? A mechanic mentioned that fuel quality could affect it.
Answer : If you drive the car hard, i.e. you rev the engine a lot,
you can try changing to a colder plug of the same type as it is running too
hot. The jerking comes when the plug starts to misfire, and if you look at
the insulator of the plug and it appears to be blistered, then it is running
too hot and a colder plug is needed. If the plug looks oily and is still
jerking, then your car may be suffering from "blow-by" due to the piston
rings being worn, and you may want to go for a hotter plug.