Yes mate. A compression tester. Cheap, at about 20 odd quid ish.

http://www.justoffbase.co.uk/Petrol-...9&category=124


You remove the plug on each cylinder in turn and then turn the engine over on the starter and it'll give you a reading. You must remove the fuel injection/coilpack multiplug or similar relay so it doesn't start on you. Then you'll have the compression figures.

If one or two is low, you can then concentrate your efforts there to see why it's low. If they're all fine time to investigate the ignition system.