Update. Managed to change the plugs and leads this weekend. They made that as hard as they could for someone with bad thumbs. Anyway it all started and run fine until I drove to work this morning and same thing happened. So onto the next items I guess. All 4 plugs seemed to be fine and looks like they have been working correctly as they were just a slight brown colour and dry. Leads were proper thick fiat ones and again seemed ok. I chucked it all away just in case as replacements arte not expensive.

Next step checking the coils and connections?

Take off your ecu... place it on a radiator for an hour to get warm... then try it on your car... if it runs perfectly ... buy a new plug n play ecu .. £55 ebay

ok, folks here that know mpis better than me... a y-reg seicento is gonna be a really early mpi seicento... so does this mean it has the micro-ecu that caused so many issues fiat changed it??
I don't know much about it having never messed or owned one - but i do recall that the issue was something to do with a faulty coil causing the ecu to get damaged.

Not saying it is this but it just jumped into my head when reading back to remind myself whats going on with this car.

Ignoring all that, I'd be inclined to replace the crank sensor - i know people always say this when a cento isnt running but its 1 plug and 1 bolt and its cheap. They don't often just fail in my experience, they get worse and worse until they next stop. And heat can make it worse.

Just as another little thought, do you ever get the engine management light come on when its not behaving? Or has it ever flashed on and off when driving? Maybe worth reading it for any codes... it should log misfires etc, one would hope there is some code active or stored.

I will look these issues up as I don't know my faulty coils from my crank shaft. However the change of plugs and leads seems to have made the issue happen earlier in the drive than before although it has been wet down my way which may affect it. It wasn't as bad before the change? No lights come on unless it's about to stall

TDC (crank) sensor might be worth a punt..

Or as above (page 2) try a new coil - swap one of yours, drive it a bit.. then if it still misfires put the old coil back where it was and transfer the new one to the where the second coil is.. and try again. If the problem persists, it's probably not a coil problem.


Ralf S.

Thanks Ralf

If these are not expensive items I might just change them anyway as I hope to keep it for a few years. Coils are the things to the right the leads go into?

Crank sensor is where?

I think water pump and belt maybe due a change anyway as I don't know when or if these were done?

my general rule with the timing belts is if i dont know how old it is i change it, unless its obviously a new belt of course. And yeah, swap pump while in there usually as its cheap cheap anyway.

I think last time i bought a crank sensor, admittedly few years back now, was a hair over £20 - was a Magneti Marelli one i bought last, not something i would buy unbranded myself..

Coils will set you back 20-25 each, again been a while but will be around there.

Are ebay ones worth a punt as they look cheaper but I wouldn't know which ones to buy, some same they are of standard but no idea if they aint lying

most of them are the same even across different fire engined fiats... the difference is the length of wire... a punto one has a shorter wire than a cento one for example but either can be used on either car no problem, sometimes you'll have to run the wire different route to get to the connector though...

Cheapy ebay ones i'm not gonna comment on, its just on of them items i have always gone for a known brand.. Maybe i am foolish but i alway feel they are less likely to fail and being as its a part that is known to cause so many issues i just cough up the extra.

I forgot to answer your where is it question before, the crank sensor is next to the crank pulley, surprise surprise lol. But to get to it easy jack up front drivers side, take wheel off and the sensor is on the front side of the pulley, 1 10mm bolt holding it in its bracket, can't miss it. Been so long since working on a mk1 punto i can't remember if access becomes miles easier with the inner arch out but i'd think you'll be fine. You could just jack car up and go under the front and leave the wheel on, theres plenty of room on a punto to do it that way.

Its that sensor there

like i said.. Try the ECU trick

I will take a look over the easter holiday and do some of the suggested tests, I have a new pair of gloves so I don't die

Thanks all

As an update to this I never quite found the time to check it after changing the plugs and leads (although I did buy some gloves). Then after it being sat unused for a few weeks I started it to find a squealing noise and smoke coming out of the engine. I guessed it was from the belt and called a mechanic neighbour of a friend. That turned out to be the alternator jammed solid and this needed replacement with a new belt. So while he had it I asked him to check what was causing the bad running and instantly he said the coil pack or in the loom. Luckily it was one of the coil packs. So for £270 I have a new alternator, belt and coil pack with a receipt, VAT and a guarantee and I didn't even get dirty. Thanks for all your advice as it was this that meant I could explain some of the issues to the mechanic in the first place

I think I might change the other coil pack as a precaution and look into some of the other things mentioned on here as well

Ok I spoke to soon. Lost all power after 2 days of seeming to be fine. Gonna change other coil pack and test that and then replace the other bits mentioned

Other coil pack changed and still have the issue. The crank shaft sensor and ECU next on the list lol

I bought a cheap OBD2 fault tester thingy and it shows Ignition Coil A primary/secondary circuit and fuel trim bank 1

Any ideas if these point at a particular issue like the ECU?

Numptey said:

I bought a cheap OBD2 fault tester thingy and it shows Ignition Coil A primary/secondary circuit and fuel trim bank 1

Any ideas if these point at a particular issue like the ECU?

Click to expand...

I dont think that it is an ecu problem. I believe that you have problem either with the ignition coil sparks etc or a wiring problem.

What code does the fault appear?

it doesnt show a code just the message. ill check the wires again. what woukd cause the spark issue?

Correction it does show the codes and these are P0351 Ignnition Coil A and P0170 Fuel Trim Bank 1.

As the coils have been changed should I clear the codes and drive it again to see what then fails and shows up?