Fiat punto running roughly. - Reggie
Tonight my daughters "P" reg Punto suddenly started to run very roughly, idling badly with no power when driving. I thought it may be coils, plugs or HT leads, but all plugs are sparking, and on removing the HT leads on the coil one at a time, (and then putting them back) all drop the revs and one lead off at a time will stall the car, suggesting to me that the sparks are there with the engine running.

I am at a loss at the moment, as I was sure it was electrical. Tomorrow, I will check the timing belt markings although on initial inspection I can see no reason for it to jump as it feels to be the correct tension and I replaced it and the eccentric pulley a year or so ago. The oil was below minimum on the stick. Could the camshaft have partially seized and caused the belt to jump?

If it is a fueling problem, could ther Lambda sensor cause symptoms like this? I suppose the only other thing to check isthe crankshaft pulley sensor. Would you just clean this. The only other strange thing was that there was a "metallic sound" when it was at higher revs. I didn't like the sound of that.

Any experience with these engines anybody?

Reggie
Fiat punto running roughly. - Kingpin
I presume it is a 'FIRE' 1.1 or 1.2 engine which is quite simple - you have checked the obvious except a fueling problem. Symptoms suggest fuel starvation if you have eliminated duff sparks. As you say it won't be difficult to inspect the timing belt and see if the marks lign up to confirm all is OK.
I don't know if a dodgy lambda sensor would cause such severe problems. Is it really flat with no power at all when you press the accelerator, does it idle smoothly?
I once had a car that was very flat with no power (wouldn't go over 50mph) - turned out to be a blocked exhaust restricting the engine - not that it will be in your case but something to eliminate after checking out the fueling situation.
Fiat punto running roughly. - Reggie
It only just maintains an idle, and is very juddery, which is why I suspected ignition.
Fiat punto running roughly. - Collos25
I believe there is a temp sensor which controls the steppermotor this is prone to go on Puntos causing all sorts of weird running problems,I recently changed one for a neighbour and cured the problem whether this is the same problem as yours I would not know but worth a look.
Fiat punto running roughly. - Reggie
Yes, thanks for that Andy, I'll take a look.
Fiat punto running roughly. - Reggie
I think that I have found the problem. The head gasket has gone between cylinders 3 and 4. Compression is right down on these. I'm suprised though that it hasn't lost any water. Well that's my weekend taken care of.

Reggie
Fiat punto running roughly. - Collos25
They only loose water when the gasget has gone pot water channel or water to oil channel ,if they go pot to pot you will get what you have got very poor running but all will be revealed on Saturday.
Fiat punto running roughly. - Reggie
Yes, I hope this is the problem and it is not something else that I have missed.

I was a bit short of time yesterday to fill in the detail. Pots 1 and 2 are making 180 ish psi on my old budget compression tester and pots 3 and 4 are making about 60psi. Also I notice with all the plugs out and the tester in say pot 4 there seems to be noticeable petrol vapour coming out of pot 3s plug hole and visa versa with pot 4, but the petrol vapour isn't noticeable when I test pots 1 and 2, so I also assume I'm seeing when testing pots 3 and 4 I'm seeing two cylinders worth of petrol vapour out of one, making it "noticeable"....if that makes sense. Anyway thanks for your help. As you say ....all will be revealed.

Reggie
Fiat punto running roughly. - Reggie
Well the head gasket is broken between 3 and 4 as suspected. No. 4 piston is clean with no carbon deposits. I assume this suggests a water leak into this pot, although I have seen no evidence of a water leak yet, as the damage is between the nearest point on the pots and not apparently near the water jacket, but have not removed the gasket. I suppose the leak could be on the underside of the gasket?

The question is now, whether or not to skim the head. It was only run with the gasket "blown" for less than half a mile, and my neighbour did one a few years ago, again on a Punto, and had no further problems. I realise the correct failsafe thing to do is to skim it, but on a "P" reg car would any of you risk it? What are the chances of it recurring if I didn't skim it, based on the fact that it did not boil the head.

Reggie
Fiat punto running roughly. - RichardW
Check the head is flat with a steel ruler and feeler gauge. However, given the propensity for these engines to lunch head gaskets, getting it skimmed seems the best option.

I did however do a BX TD head gasket without skimming the head and it was OK....
--
RichardW

Is it illogical? It must be Citroen....
Fiat punto running roughly. - Chris M
A skim should only cost you circa £20 - £25 and can be done without striping the head down. Not worth the risk in my opinion.

Chris M
Fiat punto running roughly. - Reggie
As a skim is going to be only £29.00 so I have decided to take it down for a skim, and also it should be ready in about 3 hours, so common sense and safety has prevailed.

Apart from the reasons given above, I wasn't sure just how much it was going to cost or if it would have taken two or three days, and the car is required rather urgently.

Thanks to all of you for your responses.

Reggie

Fiat punto running roughly. - bell boy
make sure you put the headgasket on the right way so the oil gallery hole isnt blocked
Fiat punto running roughly. - Reggie
Thanks oldman, the aftermarket head gasket didn't have a "top" or "alto" on it therefore it was a good reminder for me re the oil gallery hole. The jobs now done, and everything touchwood seems OK.

Reggie
Fiat punto running roughly. - Kingpin
I would keep a close eye on the coolant level for the next week or so Reggie, these can be tricky to re-fill without getting air locks. After a few miles the system may bleed itself and the level drop a little requiring topping up with some anti-freeze mix.
 

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