Land Rover Repair: Disco II service engine light, coolant leak, diagnostic charge

Question
I own a '99 Disco II with 86,000 miles.  Just before I passed 84,000 miles the service engine soon light came on.  I took it to the guy that works on my volvo 240 and he plugged his scanner in and we saw a cylinder 4 misfire message.  He changed the plugs and fixed a small coolant leak and the light was off.  450 miles later the light is back on, so he & I look at the battery, which has green stuff on one terminal, he cleans it for no charge and the light is off again.  500 miles later the light comes back on and blinks at me.  I take it to another garage that has worked on this vehicle in the past and they say "cylinder 4 misfire" and suggest new plug wires.  They could not get the wires so I took it to the service dept at german concepts in osceola, IN (the place I bought it) and they get the same engine code, but the service manager there said that they drove it for 20-30 minutes and did not record a misfire and also sprayed water on the coil to get it to misfire, which it did not.  500 miles later and the light is back on.  The vehicle runs smooth.  I would like to avoid another $65 diagnostic charge for some garage to tell me there is nothing wrong with it.  I have also recently moved to Lansing MI and would like an import or rover specialist in the area if you know of any.  This car has been great and trouble free until now.  Thank you for taking the time to read my lengthy question.  Your entries are always helpful.

Answer
There are several causes of a cylinder misfire

1 - A bad plug
2 - A bad wire
3 - A bad coil pack
4 - A sticking valve in the engine

Now, if the plug goes bad (1) it will cause the failure of 2 and 3 if left unrepaired.

Sticking valves is a problem that Rovers like your are prone to which has nothing to do with the ignition.

My best advice would be to swap the coil pack and wires and plugs and see what happens. If the light comes back for the same thing you will probably be looking at internal engine repair.

There is an article about sticking valves on my web site, www.robisonservice.com > service > land rover > advice.

If you find these responses helpful please vote on the feedback page.

thanks
John Robison