Basically, iv had my corsa B 1.2 16V R reg for 3 or 4 months now and up until last month it has been running fine. The problem i am having is that when starting the engine the car makes a low rumbling noise and ticks over below 1000 rpm. I have been told by a friend that it is the inside two cylinders that are not firing. I have checked the water and oil levels and everything is fine. I popped the bonet and when the car was on, the engine was shaking quite a lot. and also the exhaust is blowing and sounds a bit like a tractor when i go to pull away. When i do go to pull away however, the car shakes and jolts. Has anyone else had any trouble with something like this??