Fiat 500 running on three cylinders.

[Bullet2012]

Sounds like a knackered driveshaft, collapsed wheel bearing or CV joint
It makes a thuddin

Dual mass?
If so can cause release bearing to wear away the housing, then its new box time

 

[JOEPRO]

Plot twist- its a 3 cylinder engine!!

 

[dobbslc]

This one's a four cylinder, as least I managed to screw four plugs into the top of the engine

 

[JOEPRO]

This one's a four cylinder, as least I managed to screw four plugs into the top of the engine

I see, its the big block version then

 

[bricol]

Sounds like your kids have the same sort of parents who didn't teach them anything sensible useful in the real world as the people like the yellow ardvark complain about when he gets them as work experience/co-workers . . .

 

[dobbslc]

Nice

 

[Erie Fred]

This one's a four cylinder, as least I managed to screw four plugs into the top of the engine

....in the same cylinder......TaDah !

 

[dobbslc]

Twin spark , Fiat and Alfa Romeo are the same group!

 

[Erie Fred]

Old timer shared a trick for diagnosing some ignition problems.
Use a mister bottle of water on the running engine.

 

[dobbslc]

Sounds like you might have a coil pack issue. I had a similar problem with my car once, and it turned out to be a faulty coil pack causing it to misfire. Even though the coolant spill might have affected the O2 sensor temporarily, it's worth checking the coil pack and spark plugs to see if they’re the real culprits. Sometimes, when coolant spills into sensitive areas, it can cause trouble until everything dries out. If the misfire keeps happening, replacing the coil pack might do the trick.

The misfire is sorted (for now) there's been a whole host of other problems with this car since then!
It is the most unreliable car I've ever dealt with, it's taken the honour from the sxxt box diesel Vauxhall Zafira and that's quite something!