Long term fuel trim lucas hotwire

[swallet]

Now the old girl is back up and running after the faulty rotor arm incident I've been making the most of the Rover guage loaned to me by Peter. Fantastic bit of kit.
All sensor readouts,MAF, TPS etc seem to be within the expected range. Short term fuel trim fluctuates around 0 by +\- 10% or so.
Problem is my long term fuel trim. This seems way out.
Left is at -100%
Right is at +100%
This seems way out to me even with my limited understanding of the Lucas EFI. I'm assuming that the left O2 sensor is detecting a very rich mixture and so the ECU is dropping fuel supply and the contrast for the right which is detecting a very lean burn and trying to compensate accordingly.
Been for a very long run today and seems ok although maybe a little down on power (could be my imagination)

All spark plug connections seem secure. I'm hoping that If I pull all the plugs I might get a clue as to whether a particular cylinder(s) is/are at fault.
Any other advice in troubleshooting this would be hugely appreciated

Thanks

Simon

[blitzracing]

The two sides of the V8 are fueled completely independently, so they wont effect each other. First thing to try is an ECU reset by unplugging the ECU for 30 seconds. Id run the engine up to full temp first, then switch off and reset the ECU and then replug it. The long range trim should drop back to zero on both banks. Now start the car and let it idle for a couple of minutes. If there is an underlying fuel issue you should see the trims slowly move back to the original settings. This is just a check to see that the values RoverGauge is displaying are genuine trim values. You have to appreciate that there are multiple versions of software in the ECU's over the years, and all RG does it look in a specific memory location for the values. If at some point Lucas moved these locations you could get some very odd readings, so start here. If everything works as expected, then you could simply swap the probes from one side to the other and see if the readings change. If the probes are working correctly they should not change. A knackered probe that is not switching correctly (ie near 0 volts) will give a very high adding fuel trim value.

[swallet]

Thanks Blitz. I've been reading your previous posts with interest!

I'll try the above and feedback.