I have recently encountered a problem with a knock when the engine first starts the usual bag of spanners noise with black smoke coming from the exhaust. It subsides when the engine warms up and it doesnt appear to be lacking power. I have noted the previous observations made on the site but they all appear to have no problem with a laptop diagnosis. This car has been plugged into a laptop and it wont talk to it. The only thing that I can note is that the warmer has been diverted to a push button and not directly from the key ignition. It is also failing emissions for mot. any ideas please?