looks like the piston ring seized up and broke the ring land at the top.

 

wouldnt there be some scoring from that?

 

Sorry man but I think you are clutching at straws here. I don't see why the broken part should have rounded edges. Detonation snaps things.
From your own evidence.....

1. Changed the exhaust system with no mention of tuning to compensate for that.

2. Ticking/knocking sound from the upper engine under load.

3. Lean code cleared but not investigated

4. Chunk missing off the piston.

I'm with JMC and will say that these are all classic signs of detonation. The missing chunk could have been blown out of the exhaust. Stranger things have happened.
Combustion chamber temps when they spike have little effect on coolant temps. It's all over too quick.

 

Yeah I see what you mean. So how should I begin to tune my engine to compensate for my exhaust system? I am going to install the 02 simulators (which I am assuming goes into the secondary 02 sensors where my cats used to be). I have a duel 2.5 inch with a 70 series magnaflow duel in duel out muffler. What steps should I take to diagnose what is causing detonation. I do think the timing chain was off a little so I will fix that problem during reassembly.

 

New pics of piston from cylinder 2 are up:

https://www.f150online.com/galleries....cfm?num=13781

 

2 choices for a modded engine.

1. Go to a local dyno that you trust and have them tune your truck.

2. Go to somebody like Troyer Performance or similar for custom tuning through a handheld device like an Xcal2 or Predator.

 

I don't buy it. That missing chunk is old. look at the soot deposits on the break. Something is going on, but it isn't detonation. I think something mechanical is broken. (besides the piston) This is very unusual. I wonder what it looked like when they put it together...

 

i agree with chester there... somethings not right with your statements... it looks like deposits on the break, unless thats the color of the material throughout?

 

Thats what a few of mechanics told me. The material is cast aluminium so it would be a light grey in color. Hey get this too, one entire bank (undamaged side) had the wrong plugs in it. I think they were just a different heat rating but yeah they were all wrong. The damaged side had 2 of the right plugs and 2 more wrong ones. I suggested that the shop told their apprentices to have at er when this engine was ready to put in and, like I said, maybe someone dropped the darnded thing and they used the broken one anyway to cover up what they did. Who knows. Again, even with the ticking, right before I had a misfire the truck ran good. Idled good ran smooth hardly could hear the engine from inside the cabin on idle, started in cold weather great. I figure if I did a compression check I would of goten full or near full compression. So again all these facts leave me very confused as I am thinking it is leaving you guys too.

 

the piston could have knocked the head.. how does the head look? the only time one of my buddies broke a ring land they missed a gear and the piston hit the head.

 

you making excuses?

 

Head is fine really good shape.

 

hey now i wouldnt go that far, wait til you pop the caps to the cam journals and look at their condition before you get too excited. lol

im sure everyones still saying detonation issue and that may be correct still. im not seeing anything to justify otherwise, but the buildup on the fractured edge is kinda odd, meaning it has some time on it that way... no scoring of the cylinder wall?

 

Cylinders are spotless...

 

Please take some pics of the head. And look at them closely. The valves too.... There's no way that big of a piece of piston broke off, and it didn't even bend a valve, or score a valve seat, or scratch off some of the ceramic coating, or scratch off some carbon deposits or something!!!!