UK-POLOS.NET - THE VW Polo Forum

I have a 2003 1.2 polo with a misfire, i thought it was the common coil but this isnt the case, its misfiring on cylinder 3, if i unplug the coil the car still runs, but if i unplug any other it cuts out, i swapped the coils over but its still the same, so i took the plug out, it was a little wet and dirty so cleaned it but still the same, so i swapped plugs, still the same, i took the injectors out but they are all delivering fuel so its not that, any ideas guys as its doing my head in now, the only thing i can think of is a wiring fault,.

hi mate, I'm not sure to be honest but i have one of these polos, when my dad owned it before me, the thing was misfiring bad,, aster doing the coil check it turned out to be the cat,, new one on and ran like a dream,,, have you googled 1.2 cylinder problem, although i think its no1.not sure, its something to do with a timing chain skipping a tooth, so uprated chains to go on, or something with valves.it was what i was told on another forum..sorry i can't be of any help but let us know how you get on.I'm purely guessing here.

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Did you get to the bottom of this problem yet. It has been reported, by a Tech, elsewhere, that this can be caused by a faulty injector that is causing overfuelling.

lamber sensors? Controlling the injection to the cylinders through the ECU to make the car run right. If the lamber sensors are covered in carbon/sut then they wont be working as well as they should be. You can try take them out and wire brush them up. Or take it out and run it with out 1 (Be prepared to be covered in crap) If it still does it I recommend you replace it. Then if that doesn't work then its something off the list to check.
Good Luck!!

Well, for what it is worth, my advice to someone that has taken their Lambda sensor out and scrubbed it up with a wire brush, would be to place it in the rubbish bin - what are you like?!?

Fair enough. Done it before carefully and it works so cant knock it. Just be carefull

I'd think that if the Lambda sensor has become "lazy" - ie is causing the rich>lean>rich switching to be too slow, and there is no other logged Lambda sensor fault codes, then cleaning it up with carb cleaner might just make it a bit more responsive, but first you would have to had a look at what the Lambda sensor is actually doing as opposed to what it is expected to do.

I still think, that after what the OP has reported doing already, the second poster is is nearer the mark with "slipped timing", or me with over fueling, or/and maybe a valve or its seat is now burnt. While not gospel, there is (forum) talk of these engines suffering these three problems which will cause a misfire.