fast question 1990 525i m20 e34

i have a 1990 525i m20 engine
just installed it. it had a horrible knock and i decided to check the spark plugs cylinder #5 was the only brand new looking plug the rest were already black. my question is if the fuel injector on cylinder 5 wasnt working would it cause a noise that sounds like a baseball bat against a rock?

Well, it would seem that cylinder is not firing for some reason. I guess the injector or injector connection could cause this. Also a bad plug wire, or distributor cap.

I do not know if that would cause it to knock, but I wouldn't be surprised...

Are these wires, cap, and injectors ones from the old engine, or did they come on this "new" used engine?

If not the injector, plug wire, or dist cap, I can't think of anything else that would be good news...

Last time I had engine problems with my M20, it broke the two rocker arms on Cyl 5, for no good reason I could determine. I somehow managed to replace them without pulling the head... don't ask... it wasn't pretty.

When I put it all back together and adjusted the valves (rocker eccentrics) it ran OK, but had a loud tapping sound.... turns out some of the valve adjust nuts were partly stripped and did not hold the adjustments... I had to order new nuts, bolts. But I do not think this is the same... I think in my case #5 was firing.... but I did not look at the plugs... they were all old anyway and would have been "dirty".

Have you done a compression test on this engine?

Good Luck. Let me know what you find.

i ordered the plugs wires distributer cap and rotor and coil all new since the new used engine didnt have any of them im going to try to swap out the fuel injector with one from my old engine which i know was good and hope for the best will let you know what happens tomarow.