Some weeks ago my Fabia 1.2 (AWY) started to misfire, first during heavy acceleration and later during normal use. The logged code said the misfiring cylinder was #2, so I changed the coil pack on the middle cylinder. This appeared to fix the problem for a couple of weeks. Then there was a momentary drop in power (only) when accelerating on full throttle and passing about 2800revs/min but the engine warning light staid off. Another week or two later I see an intermittent loss of power during acceleration and the stored codes blame misfire on cylinders #1 and #2.

 

Should I still be changing coil packs, or should I let someone who knows what they are doing have a look? I have had two coil pack failures in the previous 10 years of the car's life, and replacing the suspected pack provided a reliable fix both times. The difference now is that #2 is still misfiring with a new pack (though one bought on ebay) and the computer takes a lot longer to illuminate the engine warning light. Previously the light would come on even before a misfire was obvious (and would stay lit before possibly going out days later). Now the light illuminates for a short period after attempted heavy acceleration but goes out soon afterwards.

 

Any hints/suggestions would be greatly appreciated. Also, could someone please tell me which is cylinder #1 and which #3. Thanks again.

Did you inspect the sparkplugs before fitting new coilpack?

 

No.1 cylinder is nearest the aux. belt end.

Did you inspect the sparkplugs before fitting new coilpack?

 

Many thanks for the reply. I didn't check the spark plug(s) because the onset of the problem was sudden and its severity was also inconsistent with slow deterioration. The current spark plugs have been there for about five years and 25k miles. I'll check them in the absence of suggestions along the lines of "changing all three coil packs twice fixed this for me". Thanks again. 

No problem.  There's a part of me that says worn-out sparkplugs might well cause coilpack failure. I don't have practical experience to back it up, but it's well worth a look I'd say. If the spark gap (on a worn-out plug) is much larger than Haynes specifies, the energy required to jump that gap will be higher, so maybe more stress on the coilpack?

Edit: Or simply, the voltage generated by the coilpack is insufficient to bridge the gap, so that cylinder misfires, but the fault isn't the coilpack being too weak, it's the gap being too large?

Spark Plugs need inspected.

Failing Spark Plugs are often the cause of Overheating Ignition Coil Packs.