M-20 J (201) / Allegro
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 300; Flight Crew Total 2600; Flight Crew Type 2000
Time Pressure; Troubleshooting; Communication Breakdown
Aircraft Equipment Problem Critical; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Aircraft Equipment Problem Dissipated; Flight Crew Landed As Precaution
Human Factors; Aircraft
Flying to ZZZ. Approximately 7nm NE of ZZZ at 4000 MSL. I was being vectored for a visual approach runway 18. The engine started running extremely rough to the point I felt like it was going to quit. I told the tower controller that I had engine issues and needed to land immediately; nearest runway. I didn't hear a response; or it sounded like the Controller was giving instructions to another plane. I turned directly towards Runway 13 and started descending. I felt like I had enough altitude to make Runway 13 if the engine died; so I started troubleshooting. I tried switching fuel tanks; no joy. I tried different positions on the key switch; no joy. I tried cycling the fuel tank selector; again; thinking that maybe I didn't quite select the opposite fuel tank detent. The engine started running a little better; at least to the point that the throttle was responding to power changes. The Tower Controller asked me if I needed any assistance; roll the fire trucks; I replied that the engine was running better and I knew I could safely land the plane. It was after I landed that the ZZZ Tower Supervisor called me and said there was a possible pilot deviation in that there was a Hawker jet below me when I started descending and that there was a loss of minimum separation.
M20J pilot reported communication breakdown with ATC while troubleshooting engine malfunction; resulted in an airborne conflict.