V-reg 1.2 Fiat Punto idle problem

[KITT]

My mum's Punto has developed a slight problem when first started. At idle it sounds like it's running on three cylidnders but is fine when you rev it. Once it's warmed up for a few minutes, it's fine.

My inital thoughts are plugs/HT leads but surely that'd effect it through out the rev range and not just at idle? Any other thoughts folks?

[KITT]

edc said:

Try the coil

It's got twin coil packs mounted on the side of the engine. I thought it's quite rare for one to fail?

I've not actually changed anything yet, but was wondering if it's worth changing the leads and plugs? I would have thought if either was at fault then the who rev range would be effected, not just idle? Don't want to go changing stuff that'll have no effect

[KITT]

Any way to confirm whether it's the lambda sensor or not? I would have thought they'd be a warning light if it was at fault?

[KITT]

deltafox said:

Multimeter on volts range applied to the signal wire and the other to earth. Reading should fluctuate up and down between 0.9 and 1.1 volts if its stuck at say 1.0 volt and theres no apparent fluctuations even when revving, itll mean the lamba sensor's had it.

Cheers! I'll give it a go this weekend

[KITT]

She said it's got worse and now does it even when the engine's warmed up. No mayo in either the oil or water, so don't think HGF (yet!). Thinking about it, the exhaust was changed a few months back, so perhaps they upset something that's now surfaced.

I'll check the lambda at the weekend (can't be arsed to go crawling round under cars in the evening!).

[KITT]

theconrodkid said:

whip the plugs out,if there is a "fungus" or different colour on 2 or 3 its gasket time

Not liking the sound of this! I'll try and check them too but as I don't have a Haynes manual, does anyone know what torque they should be done back up to? I notice it's an ali head and don't want to shaft the threads.

[KITT]

Oh dear oh dear oh dear!!!

1pm I get a call from mum saying she's broken down. Steam everywhere water and oil lights on etc. Engine so hot that the plastic cam cover had melted where it attaches to the head.

Yup, the head gasket's more than lightly gone south. I did mention to her that if any lights come on (hasn't got a temp guage) she should stop straight away, but she drove 4-5 miles with the temp warning light on!

I drove out to rescue her and could see the engine was VERY hot. AA man took the thermostat off and it was bone dry. No water in the engine at all and the level was way down.

So, how easy is it to change the head gasket? I've changed the Tiger's one easily enough. I would expect the head's warped too as it was seriously hot. Engine will still run if you start it with no warning lights, so it has oil pressure.

[KITT]

theconrodkid said:

head gaskets are a doddle on these engines (fire?).remove with inlet manifold on and exhaust mani off,new timing belt and check pump isnt foobard,always get head skimmed

Don't know if it's a Fire engine or not (1.2 8v, ali head says Lancia on it).

I guess a Haynes manuals would be a good first step(?)

[KITT]

Well, it seems the head gasket didn't fail as the compression tests came up good and there's no oil/water mix The culprit was the inlet manifold gasket. As this is water cooled, it was allowing coolant to drain into the engine which was being burnt off as in ran. Hence why it over heated. Hopefully it'll be ok now, but as the car's done 29k I know the head gasket can't be far off failing. Time to sell it me thinks!

[KITT]

Ok, I was a little premature with my last post. It's still loosing water and has a rough idle Could it still be the head gasket? Compression is good on all cylinders and there's no mayo anywhere.

Suggestions folks?