Hey guys. I got a pretty loud knock happening with the old Cummins and could use some help identifying it. My alternator went out on a business trip this week. In an attempt to limp the truck to the next town I ran it dead. I had a new alternator put in it and got it all charged back up. 

When I fired it back up it was smoking a lot I had a miss and knocked real bad. I put about 20 miles on it and the miss/smoke went away but the knock is still there. 

It changes up and down with engine speed. I have checked under the hood or tools left over belt issues and anything obvious. Boost fuel pressure and exhaust temp are all normal. 

No check engine light but I will pull codes next time I get a moment. 

Any help would be greatly appreciated!! 

Wouldnt that cause a miss all the time though? It runs perfect after a cold start, just misses when hot.

My 02 would have a slight intermittent stumble/miss at no load hot idle in neutral or park, turn the ac on and it was smooth as could be or put it in gear and it would smooth out as well once it had a light load on it.

I just dismissed it as a nonissue and never worried about it.

Edited August 31, 20168 yr by Wild and Free

Just thought I would update on my new engine. I have about 5-6k miles on it now and I think the rings finally seated as it finally stopped using oil. Everything has been running great and smooth. I am still having the slight mis-fire after the truck gets all warmed up. Seems to be getting a little worse actually. It still runs perfectly smooth and even right after start up but once its up to temp it sounds like one or two injectors are not firing properly or at all. I cant see any obvious leaks and I am pretty sure its not growing oil. I am going to get a hold of DAP and see what they have to say. Thats where I got the new RV275's from.

 

Any other suggestions in the mean time? I was going to go through and see if I could at least narrow down what injector is messing up. Maybe even trade it with another and see if the problem follows.

I'm in the same boat for the time being the only thing is I've got more miles on my injectors. My misfire is only at fully warmed up state typically noticeable after running hard on the highway. My first set of RV275's failed basically when the pop pressure fell out to about 240bar. Now I think this set of injectors are head the same direction being I've cleaned them up and the whole bit but still got a random warm idle miss. Now mine I can explain to wear... As for you is a quality control problem most likely. 

Well I called DAP today. Mine are actually still under warranty. They said just send them in and DAP will pop test the set for free. If there are any that are out of spec they will be replaced. Time will tell what happens I guess.