Join Date: Oct 2002
Location: Home of the Nimbus
There could be numerous reasons for this. On my previuos Alfa 33 16V Q, I had the same fault traced to one cylinder, which was 15% down on compression compared to the others. This caused an imbalance in the firing cycle, but it was only detectable at idle. Once revolutions picked up, flywheel inertia and overall momentum increased this imbalance was equalled out. Had the cylinder worked over with valves, piston rings etc., cured the problem.