Knock knock?

Evening fellas,

As I await to finish the finishing touches to put in my rebuilt engine (funds do not permit me to do so, also clutch and fuel pump)

I am currently going through a very bizarre situation, at first I thought it was the e10 I put in that caused an engine ping, this was not the case as I drained the e10 from the fuel tank, fuel pump, fuel lines, fuel rail and fuel injectors, I put in a fresh full tank of Premium 98 with Octane Booster, this did not solve my problem at all.

The engine has around 242k on the odo and as such I have been using a thick "high km formulated" oil which was "Engine Extender 25w 65" I just recently done a complete oil change and oil filter change using the Shell Deluxe or something 15w 55 as recommended by the book. I have since noticed a very high pitched knock of some sorts between the RPM range of 1800~2800 RPM. It's inconsistent and doesn't do it all the time, mainly up a hill.

I have gone through EVERYTHING, the injectors resistances are all 15.8 oHMs, the wiring loom is reporting A-OK, I have a fault code which was for Injector, using the old screwdriver stethoscope trick I can hear the injectors ticking away. It also misfires crazy.

Any thoughts?

Is the knock out of the tail pipe or the engine?

Knock from the tailpipe is constant, the "knock" from the engine is dependent on load and at around 1800~2800 RPM.

In saying that I also have zero idea on why there is a knock from the tail pipe lol.

That is most likely a death knock from a big end bearing. The reason it happens at those revs is the piston is floating so not on load and not on decel. Unlucky break.

It's very strange, it only happens when in motion and up a hill. Cruising, idle, idle revving, acceleration, deceleration, all good. It's strictly under load and those RPM's. I wouldn't be surprised it it's the big end bearings, I know the piston rings have failed, it's like a wind tunnel when you open the oil cap lol!

EDIT :
Also this could be a very old problem as I done a complete oil and filter change to a much thinner oil, this problem has only purely surfaced since the oil change.

Take off the sump and have a look at the bottom end, considering how bad that sounds id expect to see a heap of metal fragments and shavings in the oil.

My old 4g15 would make a knock (very similar to the vid) when the 15w-30 oil would reach 110c, because the oil was too thin for the temps.

I put an oil stabilizer in aswell as some thicker oil and the knocking sound is still there, I haven't popped open the sump yet. It's very strange, I'm suffering no power or torque loss but there is quite a substantial misfire and still an error code on Injector #4.

Starting to have my doubts on a critical component knock... I put a camera down through the spark plugs and everything is fine, nice and clean and not metal shavings around the place. I'm starting to think maybe an injector possibly isn't firing or my spark plugs are actually completely knackered?

Fixed lol, timing was wayyyyyyyyy out.