hi, i owned a wira 1.3 injections year of makin 2003. the car was using semi synthetic oil since the start n never missed an oil changing schedule. Recently, the car have a few problems. Early morning when i start the engine, the idling were not stable even after it has been warm up. And the dashboard meter showed an "engine check" sign even when i start to drive the car. After a few hrs of driving and park it with engine still running, there is a scent of petrol humes from the exhaust. (feels like the burning was not complete and it does consume extra fuel than normal about 0.25cent - 0.27cent a liter to the current fuel price of rm 1.90/liter). Then i open up the hood, n hears a "tapping" sounds in the stepper motor, and i seen some stain(oily or petrol stain, not sure) on the outter surrounding of the placement of the spark plug. Got it unplug, n i see a carbon accumulating it even i only uses it for only 2 months or so. i check my exhaust tail, it has a lot of carbon with sometimes throw up some liquid like substance and it smells like petrol (i use the car only 1-2 times a week). Other symptoms were there is a bubbling in the radiator cap with some rusty dark brown colour on it. ( currently i didnt use a coolant). ive check the dip stick n open up the oil cap, there is no "blow by" n no lost of engine oil. Does this symptoms i need to overhaul my car cos my mechanic says so?... 
thnks
thnks
