172 misfire/hesitation fix *fixed*

[r516vt]

Had a prob with my 172 last night, it was for a period but then started misfiring and hesitating. It was prettyh obvious the car was running on 3 cylinders with the 4th firing but by no means properly, this resulted in some quite nasty backfiring and serious hesitation under load. I drove higher in the rev range and it was not as bad but still very noticeable, the exhaust was stinking of unburnt fuel as well. Shortly after the problem developed the engine management light started flashing.

Diagnosed as a failed spark plug on cylinder #2 (counting from gearbox end), seems as though water had leaked passed the plug seal under the valve cover and into the plug recess. The plug was quite rusty where it meets the lead. I replaced that plug and cleaned all the others, put the car back together and it is running fine again.

Thought this might prove a useful post in case anyone experiences the same.

 

[happycallis]

I had the same thing mate but on #3 plug instead.

 

[Ridahz]

Thanks for the heads up mate

May prove useful in future

Cheers!

 

[RichCup]

Had the same, although I replaced all the plugs and leads and it still hesitates when cold every now and then