You just want to see all the rockers moving equally while cranking the engine. If not there's a cam or chain problem (or bent push rods but that would be obvious). But now, hearing that the wiring issue was found at the time of failure, it's more likely to be the problem. The confusing thing is that you have low compression too. I don't think the engine would keep running long enough to do internal damage once the ECU failed. Unless you had bad enough luck to have electrical and mechanical failures at the same time. I'm officially confused. I would try an ECU first. With the disclaimer that I don't know which wires you are talking about, exactly, and it could be anything related in any way to the damaged wires, not just the ECU, or the ECU at all..

 

Here's a simple way to do some minimal checks of the ECU with key on engine off, with live data from your OBD scanner. Check throttle position, it should follow as you press the gas pedal. Check engine coolant, fuel rail, and intake air temperatures, they should be at room temperature. Look at MAF and O2 sensor voltages to make sure you are getting some readings (I forget if O2 voltage is high or low, but it's one or the other). There might be other things you could check to see if values are normal. If everything looks reasonable, the ECU is probably OK, and vice versa.

On the mechanical front, if you get good cylinder pressure after adding a spoonful of oil, then rods and valves and timing chain and cam are all OK. The oil simply helps the piston rings seal better.

 

Hello all, after a long hiatus I finally got back to tinkering on the Rover this weekend.

CONCLUSION: The bolt holding the cam sprocket had backed out almost entirely. The sprocket was not being held in, and the bolt was about 3 full turns (by hand, no tools needed) from coming out completely and the timing chain slipped off into my hand before removing it fully.

I wonder if anybody has experienced this before. I'm guessing with my limited knowledge that the bolt loosened incidentally, and the timing chain jumped as a result? The chain and gears all look fine but I will be replacing them shortly as I put this back together.

If this sounds wrong please correct me!