Fiat 500 running on three cylinders.

[dobbslc]

The youngest sons Fiat 500 is intermittently running on two or three cylinders (1.2L 8 valve engine) . I'm not sure when this started but I had to replace the thermostat housing yesterday as the plastic pipe had snapped off loosing most of the coolant.
The post CAT O2 sensor plug was full of coolant so I cleaned it with brake cleaner as that's all I had but I wouldn't think a dodgy O2 signal would make a car run on three cylinders
It then seemed to run well after the coolant and cleaner had dried out.
To reach the stat housing you have to remove the ECU and a few other connectors but I've checked these and they are all plugged in ok
Coincidence or does it have a dodgy coil pack?
Fix It Again Tomorrow

 

[lazybones51]

If you can isolate which cylinder isn't running, you could try swapping the coils around (are they stick coils on the later 1.2s?) and see if the problem moves. I know the older generation 1.2 8v used a pair of coil packs, but I can't remember if they changed them on the later cars.

 

[dobbslc]

It's a solid four cylinder coil pack on this. I pulled each plug lead off while it was running and all were firing at the time.

 

[mr haynes]

Should notice a change when you pull a "good" cylinder.
Check resistance is same across the leads.
Have you pulled plugs?

 

[dobbslc]

Should notice a change when you pull a "good" cylinder.

Sorry that's what I meant.
Plugs were new a few months ago but I'll check them.

 

[Smallfry]

Maybe coolant down the spark plug wells, shorting it out ?

 

[Dave H2]

If you can see the exhaust manifold, wet it, and start the motor, last one to dry is the missfire

 

[dobbslc]

Maybe coolant down the spark plug wells, shorting it out ?

Theres no way for coolent to get up there as far as I know, I'll have a look just in case

If you can see the exhaust manifold, wet it, and start the motor, last one to dry is the missfire

The exhaust manifold is the last thing I want to go near on this thing! It has a heat shield that will almost certainly snap the bolts if I try to remove it
It does have a very slight blow as well, they are known to snap the manifold bolts as the exhaust gets clumped on speed humps.
It's been running ok since though. I hate 'fixing' something without actually fixing it
It had an advisory on a worn inner track rod end and I give it a quick check yesterday, it's quite bad so needs doing but I'm only 3 weeks in after a knee replacement so I'm gonna struggle with this! The upside is it needs a special tool to undo the track rod so I can at least be justified in a new tool purchase

 

[Crosshair]

Pull the plugs out and see which one looks different
From memory these 8v units used to fail HG on cyl 1 , did you check b1s1 o2 for coolant

 

[dobbslc]

It's been fine since...

 

[Erie Fred]

My sister has one....I thought it only had qty (3) cylinders.....who woulda thunk it ?

 

[bricol]

I'm just struggling with parts of two sentences . . .

"youngest sons Fiat 500"
and
"I'm only 3 weeks in after a knee replacement so I'm gonna struggle with this"

 

[Bobupndown]

My sister has one....I thought it only had qty (3) cylinders.....who woulda thunk it ?

Some do.
They did a 2 cylinder (twin air) 3 cylinder (hybrid) and various 4 cylinder engines, including a diesel and the 1.2 8v petrol which is from the ark, not counting the turbo Abarth 595, 696s.

 

[dobbslc]

Still had a slight coolant leak so took it apart again and found a duff jubilee clip that went tight but wasn't clamping the hose properly
I also fixed the oil leak that I thought was the rocker cover gasket but looks like it was the camshaft position sensor that was missing it's O ring! New O ring fitted.
Touch wood it's ok now...

 

[dobbslc]

More troubles
Last week the gearshift cables snapped so that was sorted out at the weekend along with an oil and filter change whole it was jacked up.
After a bit of adjustment it's working ok and the dash is back in.
Then "Dad it's making a noise and there's a light on the dash"
The warning light I think is just a blown brake light bulb but the noise...

Sounds like a knackered driveshaft, collapsed wheel bearing or CV joint
It makes a thudding clunking noise even in a straight line

 

[dobbslc]

Oh I think I forgot to mention that the thermostat housing split a few weeks ago spilling most of the coolant out.
Another common fault apparently...

 

[Hotstuff]

Ownership of the Fiat sounds like a war of attrition.

 

[Bobupndown]

More troubles
Last week the gearshift cables snapped so that was sorted out at the weekend along with an oil and filter change whole it was jacked up.
After a bit of adjustment it's working ok and the dash is back in.
Then "Dad it's making a noise and there's a light on the dash"
The warning light I think is just a blown brake light bulb but the noise...

Sounds like a knackered driveshaft, collapsed wheel bearing or CV joint
It makes a thudding clunking noise even in a straight line

It's seems like a full time job looking after the family fleet these days!
I've a clutch to replace on a Peugeot 108 and discs and pads to do on a VW Polo this weekend.

 

[dobbslc]

I have some good news!
The knocking is fixed I jacked it up and took the NS wheel off and had a really good look and prod but couldn't find anything wrong but I did think that the wheels nuts came off really easily! Mmmm.
I cleaned them up and refitted them and took it for a drive and the noise has gone so it was loose wheel nuts.
I was a bit pizzed off with myself as I'd had both front wheels off the do the knackered tie rods a few weeks ago and had torqued them up so I thought I'd test the 1/2" torque wrench against my 3/8" one and it did click off too early!
So it looks like I need a new 1/2" torque wrench
The dash light has gone out after the boy replaced the blown bulb (he's really proud of himself about this) and the gearshift is much better than it ever was
I can put the petrol and matches away for at least another day...

 

[Bobupndown]

The dash light has gone out after the boy replaced the blown bulb (he's really proud of himself about this)

My kids wouldn't have a clue and have no interest to learn. It's just "Daaad... my cars making a funny noise / broken / got a flat tyre / blown bulb / needs serviced (insert appropriate mishap) can you fix it?"
It's as well that I enjoy time in the garage with the spanners.