While removing the engine in my wife's 03, l found the knock sensor wire completely smashed/grounded between the P/S bracket and head...and it didn't have any codes (besides a SAI system code, which was related to a manifold check valve issue) or misfires.

Actually ran pretty good for an engine with three slipped liners, blown head gasket (external) and no oil pressure...go figure...lol.

​​​​​​​ Brian.

 

Pretty small chance of that.

Check your spark plugs for signs of oil or coolant.

 

Unplugged the wire so I could pull it up to see the damage. Looks like the wire wasn't breached at all. Taped up the worn areas and plugged it back to the knock sensor. Now all the engine codes cleared. O2 bank 1 sensor 1 came back up. Idles smooth again. I'm at a loss. Can cylinders misfire just every now and then? I doubt it's a coil/plug/wire since it ran smooth for a week after the rebuild and today putting 20 hard miles on it. Before ya'll give me crap I'm going to put in new O2's. Thinking a reset of the adaptive settings are my problem.

 

So to wrap it up I put in new O2's. All the codes went away with no misfires! Yay. Guess a bad O2 can cause multiple misfires! Bank 1 Sensor was an old one covered in soot. Thanks for the advice guys.

 

 

I had a deformed pushrod and associated rocker. 3 bent valves as well. The place that did the head work used to do all the Discovery warranty work. They told me there was a service bulletin LR wanted them to do which involved opening up the valve stem guides I believe since valves were sticking which resulted in bent valves. Anyways the tick I've endured for the last 3 years is now gone. I think everyone runs to diagnose these motors as slipped liners whenever there is a tick.