Hi, I have a 1989 Nissan 240sx with the KA24E. I have a giant problem, cylinder #4 is not firing at all. I bought the car knowing that this cylinder wasn't firing(was running on 3 cylinders, still is). Originally the injector wasn't shooting fuel so I replaced that and it's working now. Changed the spark plug and then figured that the cylinder had really low compression(about 80psi). I tore the engine apart and replaced the rings, pistons and had the block bored .20 over. I had the cylinder head sent to a machine shop and had them clean it and replace the valve seals. Well, got everything back together using the FSM and went to fire her up for the first time. She fired right up but had the same noise/vibration as before. I took the plug wire out of cylinder #4 and noticed that #4 was still not firing. I checked the injector again, good. Checked the plug and that electricity was reaching the plug, good. The compression for #4 was now at 150psi which is normal, yet cylinder #4 still refuses to fire. It's as if there's an evil spirit in there that refuses that I enjoy this car.
The cylinder had compression, spark and fuel yet still refuses to work. I'm thinking the machine shop didn't check the head over and there's something wrong with the valves in cylinder #4. Any input I can get on this from you guys would be greatly appreciated. I really don't want to have to tear this thing apart again and get the head off to send it back to the machine shop.
Pic related: it's how I feel after this whole ordeal.