5MGE Top End Knock

[zokustyle]

I have a 5MGE that I recently just cleaned up and rebuilt. I live in an area where we aren't emissions tested, so while the engine was on the stand I removed the EGR system and did the appropriate block-offs. Now that the engine is back in the car and running, it runs great, except for a knock in the top end.

It sounds just like detonation/ping. I started with some platinum NGK 5 heat range plugs. I then changed the O2 sensor, went with a set of 6 heat range copper plugs and went a couple clicks richer with the AFM. No change.

Went rich to the point of a bumbling idle and blowing black smoke, still knocked.

Brought it back to OEM settings on the AFM and put in a set of 8 heat range plugs. Still knocked.

I went richer with the AFM and retarded the timing to zero, no change.

Figured maybe my cooling system had pockets/whatever, because I put in a brand new radiator, hoses, and thermostat. Flushed and burped the system with distilled water and water wetter. No change.

Ran several fuel system cleaners through the tank with a couple bottles of octane booster. No change. I then removed the thermostat and ran it on a cold night. I was able to drop the coolant temp sensor to the C and it STILL knocked.

It's not rod knock, it's specifically between 2500 and 3000 RPM with light load on the engine. I can go WOT and sail from 2000 to 3000 with no knock. I can make it almost disappear if I retard the timing to the point where a lawnmower would make more power than it. I timed everything to the TSRM settings.

I'm not getting a CEL, will a dead knock sensor or give a CEL?

M-series engines are not my realm, I come from JZ engines. I won't admit defeat to a 5M. Help me shut this thing up.

[CarFreek]

A leaking EGR blockoff can make a tapping/pinging sound. Also, when it was apart, did you mix any top end parts up? Valves, lifters, rockers all need to be matched.

[zokustyle]

Nope, I made sure everything was clearly labeled on disassembly, and properly tightened on assembly.

It's clearly audible down the center of the head, it isn't louder on one side or on the back.

[Push]

What type of oil are you using?? Can you post a video for sound?

[zokustyle]

I ran Rotella 15w40 for a bit to clean whatever was in there out, now it has 20w50 conventional.

I don't have a video of my car, but it sounds just like this, just when the car is run light load at 2500-3000 RPM:

[skullzaflare]

i think the guy in video might have a broken rocker arm, a bent valve, or carbon on a piston, hell it could be piston slap too. granted nissan is also timing chain, and i have heard one that sounded like a knock that was a bad T-chain guide