Hi all...just to add another cause to the list of misfire causes and solutions. My modified S3 developed a huge misfire a week ago,and I thought something was terminally wrong. After limping it down to AMD,the fault turned out to be a crack across the plastic moulding at the top of the HPFP,where the electrical connections go in. It's not easy to see,and ran across the moulding completely,and the car had no idea of how much or how little fuel it was getting. Thanks very much to AMD,who have seen a few of these now,and knew where to start looking. I should add that this has NOTHING to do with the Autotech HPFP pump internals.....it's a part of the original pump that's cracked,and not the result of the internals being altered...merely a piece of plastic fitted into the top of the pump.