A batch of fuel tanks fitted to Plus 8s in the 1988/1989 period have pickup points which could become "dry" when the fuel moves to the left under the centrifugal force created by a turn to the right. The symptoms reflect other possible problems with the fuel systems such as an intermittent fuel pump failure, improper ground or injection system problem. This can be maddening and the possibility of this problem should be quickly investigated. The solution is the fitting of new tank.
The Plus 8 ECU is often placed poorly (especially in the U.S.) and can allow water egress. Care should be taken to prevent this and a plastic or rubber covering is not unheard of. Here is what to do if it does get wet.
The problem
A RR died after drowning the computer in a river. They were near a camp-site so they prized some circuit board out and hung it up to dry, and next morning it started straight away. I don't know if this is normal. It seems to me that good clean water swiftly removed shouldn't do much harm ?
The Answer
The ECU should survive AOK, but I recommend that, now that the RR is back home, the ECU be opened up and a check be made to make sure that everything is absolutely dry. Also, take a look at the contacts on the printed circuit board(s): if they are dull looking, try gently rubbing them with a pencil eraser: along the length of the contacts (not cross-wise.)
I tell you a story about an SD1 and a torrential rainstorm, with flooding (a rare occurrence here [Canada].) The car inhaled water through the air intake. Back on dry land, the starter motor was used to pump the water out of the engine. No damage occurred to the engine; however, a year later, the air flow meter malfunctioned. When I opened it up, I found enough corrosion to give significant trouble.
The Land Rover V8s from 1999 on use the 5.2.1 Bosch Motronic system. The heads contain a NEW spark plug (or better 8). It must be replaced by the same type as the EMS relies on the varying resistance of this plug to adjust spark force and timing. The genuine is an Champion RC11 PYPB4 double-platinium spark plugs. This spark plug allows extended plug life, recommended interval is 72000 MILES! Probably a good thing if you look at the price of these little beauties. Always verify if the correct plugs are mounted. This type may NOT be cleaned as this shortens it's lifespan. You can tell them by the lug nut size: 5/8 on the new versus 13/16 on the old. If a wrong type was mounted you MUST also replace the High Tension Cable as the head on the plug have an other (bigger) diameter and will not fit the correct plug anymore. This is not visible and you don't feel it either but I trust LR on this. My personal opinion on changing these special spark plugs as expensive as these is a first timer for me: Leave it to the dealer. If you break ONE it will cost you more than the quarter hours work they charge for this. This engine is not touchable by other than a Rover dealer and only those with all the technological machinery necessary. It may produce fortunes when it is off warranty.
The Bosch Motronic is is similar to the systems used on BMW series 7/8 on their V-8 and V-12's. However an unit from such a car can not be substituted if yours goes goodbye, as Rover uses a different command set in their EPROM.