I’m about ready to pull my hair out because I am so confused. For context I just rebuilt my 5.3 LM7 with all new gaskets and rings for an LS swap along with a newer camshaft. I found out while tuning with my tuner )I have Holley terminator x and I don’t know how to tune it myself yet) that cylinder 4 is not firing and we solved that it does have spark and we just replaced all the injectors so it has fuel. Obviously then it does not have compression. I’m going to do a compression test here soon but I just don’t get how I could have no compression after a fresh rebuild. I know I clocked my piston rings and I re lapped my valves so I’m at a loss in how this is happening. Again I’m going to do a compression test but if it works and I have decent compression then what the heck is wrong? Also I pulled the spark plug and it is wet. Maybe fuel from not burning off? Maybe oil because my rings are seized somehow? I really don’t know. Any ideas could help me at all.

 

Pull the valve cover and make sure all is well under there.

 

I did just to make sure but I just did a compression check and got about 210 and then looked at cylinder one and it had 205 so it has to be a fuel issues because I used a spark light tester and it had spark. So I guess new things can be wrong and bad. Will replace and report back.

 

Remove the suspect cylinders' rocker arms and push down on the pushrods with your thumbs hard.
If you can push them down, lifters are bad.

 

If the compression is that close to the same on all 8, then it's not a compression problem.

Turn your attention elsewhere.

Wouldn't worry too much about lifters. Might cause a "run funny"; won't cause a "dead hole".

Fuel or spark. No matter what you think. Like, swap #2 & #4 injectors, wires, coils, etc. one at a time, and see if the problem ever moves to #2.

 

So I did have some extra injectors lying around and I did stick em in. It seemed the same to me so I just decided to put in a different coil pack and it seemed to be better. Whether it was the injector, coil pack, or both it seems it has really gone away. If I am wrong and do have another misfire on the same cylinder I will update