Car not running on all cylinders
the first thing that comes to mind is ignition system faults. Are the spark plug wires connected properly, in the right firing order? Has work been done on the distributer, or the engine head, recently? Ignition timing can be 180 degrees out, and the engine will still run, sometimes. If it is not the ignition system, the next most likely culprit is the head gasket, which seals the head to the block of the engine. If this gasket is breached seriously, it can cause a cylinder(s) not to fire. Is there water in the oil, as evidenced by a thick, white foam? Is there oil in the coolant? Either of these are symptoms of a leaking head gasket.
Basically, one cylinder isnt firing for one of a number of reasons. The most common cause is an igntion fault. This will cause the engine to feel and sound "lumpy", and the power would be greatly reduced. The best way to find the cylinder which is responsible is quite simple but care must be taken. Firstly if you hate electric shocks as much as I do, find a proper pair of electricians insulated pliers, and even some decent rubber gloves if you can aswell. Start the engine, and one at a time, use the pliers to remove a lead from the top of one spark plug, if the engine almost stops, or gets worse in any way, it is not that piston which isnt firing. Repeat the proccess, one at a time, you will know which piston ISNT firing when you remove the plug lead, and there is no change in the engine sound, this is your defective cylinder. Its just a case then of looking at the condition of the spark plug and asessing the cause of the misfire before carrying out repairs. BEWARE:- THE LEADS WHICH CONNECT TO THE SPARK PLUGS CARRY SEVERAL THOUSANDS OF VOLTS - HENCE RUBBER GLOVES AND INSULATED PLIERS
