Fiat 500 misfire, changed coil pack and plugs

[Lordbenny]

I noticed a couple of weeks ago that my Mrs’ Fiat 500 didn’t start on the button, it took two attempts to fire it up, it didn’t bother me particularly as the car was running fine. A couple of days ago she called me to say the engine warning lights and exclamation light in triangle had come on and the car was misfiring.
She managed to limp it home and she called out the AXA breakdown guy who, when he came over took it for a spin….obviously it ran fine! He connected his OBD meter and he said there was a misfire in cylinder 4.
So, I ordered and changed coil pack and plugs. The car started first time and fan super smooth for a day. However, ive just come back from the shops and the car is misfiring and warning light are on. I turned car off, waiting for a while, started it up and it was fine!

Any thoughts on an intermittent misfire?

Poor fuel?

Anything else you think it might be?

[abucd4]

Is it a multiair? Multiair unit if so, potentially. Had to change it on my Alfa for misfires.

[Lordbenny]

abucd4 said:

Is it a multiair? Multiair unit if so, potentially. Had to change it on my Alfa for misfires.

Thanks for the replay, no, it’s just a standard 1.2

When it was misfiring, I took out all the plugs and none of them were fouled up.

[shakindog]

Check the oil level is above minimum.
These engines can do all sorts of weird things when oil level gets low including misfiring
It’s caught me out a few times to the point it’s the first thing I check when I come across them now

[Lordbenny]

shakindog said:

Check the oil level is above minimum.
These engines can do all sorts of weird things when oil level gets low including misfiring
It’s caught me out a few times to the point it’s the first thing I check when I come across them now

Really? That’s an odd one, I’ll just finish this beer then go and check but I’m pretty sure it’s ok.

[andym1603]

Be prepared for it not to be a simple fix.
I work with someone whose daughters 500 had the same symptoms. Changed the plugs and coil pack as fault code showed a miss-fire in cylinder 2. This made no difference so off it went to the garage.
Seemingly these engines are soft and it was the head gasket that had failed. Quite a common problem he was told.
Car was eventually scrapped as beyond economical repair.

Good luck.

[Lordbenny]

andym1603 said:

Be prepared for it not to be a simple fix.
I work with someone whose daughters 500 had the same symptoms. Changed the plugs and coil pack as fault code showed a miss-fire in cylinder 2. This made no difference so off it went to the garage.
Seemingly these engines are soft and it was the head gasket that had failed. Quite a common problem he was told.
Car was eventually scrapped as beyond economical repair.

Good luck.

Thanks for that!

Just checked oil and it’s fine.

[Lordbenny]

Just driven it round the block again and it’s running beautifully.

Could it be bad fuel?

Is it ok for my Mrs to drive it and when it’s starts to misfire. Stop, turn it off then when it restarts and it’s ok to carry on driving it?

Don’t know what to do!

[Lordbenny]

Been for a/3 short lived drives and it’s noe running ok!

Do you think it could have been bad fuel?

[Mr Miata]

andym1603 said:

Be prepared for it not to be a simple fix.
I work with someone whose daughters 500 had the same symptoms. Changed the plugs and coil pack as fault code showed a miss-fire in cylinder 2. This made no difference so off it went to the garage.
Seemingly these engines are soft and it was the head gasket that had failed. Quite a common problem he was told.
Car was eventually scrapped as beyond economical repair.

Good luck.

Exact same happened to mine… misfire in cylinder 3. If I removed the sparkplug it would be fouled and cleaning the spark plug solved it for a few miles, only for the misfire to reoccur.

I eventually got rid of the car because the Fiat dealership was absolutely horrendous. The car went back to them numerous times and each time they’d charge me £ and solve nothing. I had to ask the dealership manager what have they actually achieved and am I paying them to do nothing? I expected the dealership to actually know their own car. The worst deaership and customer service I’ve ever experienced.

[Nigel_O]

If you've done the plugs and coilpacks, it makes sense to do the plug leads too.

My Panda 4x4 (same engine - 1.2 8v) had a very slight misfire under load. Plugs didn't cure it (although it helped - the plug gaps were huge). Coilpacks made no difference, but fitting new leads felt like someone had given me another half dozen horspower (yes, not much, but that's 10% on one of these cars...)

Helped fuel consumption too

[Lordbenny]

Nigel_O said:

If you've done the plugs and coilpacks, it makes sense to do the plug leads too.

My Panda 4x4 (same engine - 1.2 8v) had a very slight misfire under load. Plugs didn't cure it (although it helped - the plug gaps were huge). Coilpacks made no difference, but fitting new leads felt like someone had given me another half dozen horspower (yes, not much, but that's 10% on one of these cars...)

Helped fuel consumption too

Yes, did the leads too.

I’m pretty sure it’s a fuel issue…contamination?

[Lordbenny]

Brimmed it with Tesco Momentum and put a big bottle of Wynns fuel system cleaner in and…..no more misfires. I took it on a nice long drive including 15 miles on the M25 and it was good as gold.