I have yet to try and remove the wheel arch panels to get at the plugs (only had the Marcos since September), but I have another V8 in a Land Rover (really easy access!!!), and the plugs that went in the new engine 30,000 miles ago are still fine. Also I had a Ford V8 some years ago and the back plugs were sods to get at, and they were the ones that hadn't been changed (tiny little plugs too). So, on principle, I would say the harder they are to get at the less likely they have been changed. However I don't think plugs get eaten up the way they used to, I don't know if its because the metals are better, or maybe its the fuel (I use Shell's finest, even in the Land Rover).

Plugs can fail of course, and they also give tell-tale signs of other problems - like burning oil, and they tell you about the mixture - though not much you can do easily about that on the EFi. But these days it seems much more common for the leads to be the cause of problems. One of my friends had trouble with his VW camper, he looked at the engine one damp night and said there was a light show under the bonnet. I explained the electricity was supposed to be on the inside of the leads !! Leads can also break down internally, as they have carbon fibres in them rather than the old-fashioned copper cores - this saves you needing suppressors in the plug caps, but at the expense of reliability. Lead resistance will probably be 10kohm to 20kohm - I am not sure what the figure should be for the Rover, but if one is open circuit then the spark is jumping a gap in the lead.

Steve

There's a lot of talk these days about green transport. Well, I am ahead of the game, I already have green transport ... British racing green.