ENGINE BACKFIRING

Dear Bob

As an operator of Cessna 172S with engine , Lycoming  IO360-L2A.

fOLLOWING TROUBLE HAVE EXPERIENCE WHILE  START  RUNING THE ENGINE

"ENGINE BACKFIRING DURING START AND SHUT DOWN"

Could you please tell me the cause of this defect.

Thankk you

Regards

Zaven

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I highly recommend you take your plane to a certificated AMT before the engine quits in flight.  Probably a timing/mag problem or sticky valve.  Question, was the 500 Hour Mag inspection done?

If your engine is only backfiring at low rpm check your rpm rise at idle (about 650 rpm) when you pull to idle cut-off over 2-3 seconds.

The rise should be 25-50 rpm. If it's higher than 50 rpm then your idle mixture is too rich, or your primer system is leaking fuel into the induction system.

As stated, take it to an AME to get the idle mixture and timing checked out, as these items may seem to 'clear up' at higher rpms.