This post is about my Corsa C misfire which was completely solved. The problem was a misfire during acceleration, especially between 1500 to 2000 rpm. The problem was not so bad if acceleration was gentle but was still there. First, I was told by a qualified mechanic that it seemed like the head gasket had gone, because there was sludge in the oil. He quoted me a huge amount so I thought I'd run the car till it packed up. 7 months later the problem was the same and another mechanic told me that it could not be the head gasket as the engine would have packed up by now. I replaced the coil pack (ignition leads) and this reduced the problem although it was still there. That indicated an electrical fault, though not exactly what, and the acceleration was a bit better. All the while the radiator was losing water with no sign of from where. I paid the cost of a new radiator and the problem was reduced even more to a less noticeable misfire. That suggested that the engine management was getting the wrong information about the engine temperature and mixing the fuel wrongly, as there was insufficient coolant running round the engine giving the wrong temperature reading. Over all the car was reliable then one day it refused to start; the engine would not fire at all. So after watching videos on the internet, I replaced the crank sensor. Now the Corsa runs properly. So I would suggest that any one with the problem of a misfire start with replacing the crank (position) sensor as it is a cheap job: the sensor is about £15 in 2022. Actually, a replacement crank sensor ought to be part of the 75,000 service. And replace the radiator if water is constantly being lost. If you have a misfire or trouble starting and your mileage is about 75,000, try the fix above. A word of warning: attempt NOT the crank sensor replacement unless the car is on proper support like ramps. You will need to get properly under the car and a car dropping off its support will kill you. If you are claustrophobic then take the car to a garage for the job.
