I just graduated to my second plane A Sig 4*40 with a SuperTigre .40 engine. I was told today at the flight field that it sounds like it has an air leak. At high RPM the engine will surge or pulse. We looked for any visible signs of an air leak and found nothing at the cylinder head or the hose connections to the engine, back plate that would indicate any "blow by." Is there anything out there that would tell me what steps I should take to troubleshoot the problem and isolate the air leak?