hi my punto started devoloping a misfire again, i took it to my local garage and they ran a system scan. they found it said ignition failure "P0300" i had a look around and couldnt find any proper info. what does this code mean is wrong, my mechanic tells me it is likely to be coil or ECU as these are very common on fiat 1.2 8v (60).

Could well be the ECU. "random misfire".

Try swapping the leads to the coils over after having determined which cylinders are misfiring. (infra red thermometer, maybe).

If the cylinders don't change, it'll be that horrible pesky micro ECU. They can be repaired, whichis one hell of a lot cheaper than getting a new one. Lots of posts here, and something in either the guides or faqs.

its a generic code
change plugs and leads before anything else

Had a misfire recently. No 1 plug had lost half it's insulator into the cylinder. Made a nice mess of the head and piston crown after a few loud clicks on startup. Bosch plugs only 6 months old. Might have been early sign of HG going as well , last one was done 26000 miles ago.

For me this was bad leads.

Check those and plugs before coil packs and ecu.

Also don't leave it to long, it cost me a new cat.

If the coil is suspect don't be scared to fit a new one. If the problem does turn out to be the ECU the repairers always say to fit a new coil because coil faults can take the ECU.

This misfire is very intermittent, but has become more common with rainy,cold weather. it only seems to happen when the car has been left and not used for a week. i think it is an ecu fault, because if i turn off the car, take out the key, put it back in and start it. the car runs fine! its very strange but i think i need a new ecu. weres the best place to get one, i dont want to destroy my catalytic converter aswell!

ECU Testing Ltd will test your ecu. If its ok you pay postage & small fee. If its broken they sell an exchange ECU.
Have you examined the fault codes?

2 wise people hasve advised you to change plugs and leads
even your diagnosis of restarting the car backs this up
yet you talk of wanting to change an ecu
madness

The common ECU failure problem brings up a coil 1 or coil 2 fault code, not a generic misfire code, and will run on 2 cyls (as would a coil issue).

A generic misfire is just that- a misfire the ECU can't reliably pin down to a cause, and can be down to any number of things, including (but not in order):

Spark plug,
HT lead,
slipped valve timing,
duff fuel,
clogged air filter,
stuck open evap valve,
duff lambda sensor,
incorrect valve clearances,
etc.

Tell your mechanic to pull his finger out and not rely on a diagnostic code and the known 'common faults'. It would take him 5 mins to check the plugs and leads and rule out the simplest of possible causes.

It might even be a duff battery. Mine was lumpy at low revs with the old battery presumably low voltage was messing up the ECU.

As Danny says do the simple tests.

Just a refresh, I nearly bought a new ECU because of the same symptoms, turns out low battery, Ignore what multiscan says at your peril.
Old thread that should not be missed!:bang: Misfire at night lights on? misfire at night with rain? misfire in cold weather? Whilst idling turn on lights and electric windows does it trigger misfire? How many ECUs replaced? coz plenty instances didn't fix problem.

I had the low signal coil pack 1 error p03?? with misfire had to be ECU anyway multiscan also said low battery. I then remembered it only happened at night so put the steering on full lock and pressed electric windows and it started to misfire badly.
I am now thinking low battery causes ECU to fail just like it tends to blow bulbs, So today I plugged in multiscan and said error p03?? no longer evident clear faults, it never came back.