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gomi_otaku
gomi_otaku, Technician
Category: Car
Satisfied Customers: 3439
Experience:  VW Technician, VW FastTrack, VW Academy, VW Certified
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Fiat Punto: Hi. I have a year 2000 Fiat Punto 1.2 which

Customer Question

Hi.

I have a year 2000 Fiat Punto 1.2 which often has peoblems running on all 4.

The problem only occurs when starting not after having run for a while.

The engine only rins on cylinder 1 & 4 and act the instruction manual it should be a fuel injection failure. It´s always 2&3 which is not running.

I have tried swapping the spark plug coils, but no change.

If increasing the RPM to 3-5000 for a short period (approx 3-10 sek) 2-10 times it usually starts running on all 4 cylinders again.

This problem used to happen seldomly but now happens almost daily :o(

Any ideas ?
Submitted: 4 years ago.
Category: Car
Expert:  gomi_otaku replied 4 years ago.

gomi_otaku :

It's possible you either have a blown head gasker (since it is two cylinders side by side) or that you have a coincidence of two injectors leaking down when sitting, dripping into the cylinder and flooding it.

Customer :

Hi, Compression is fine on all four cylinders.

Customer :
Customer :

I guess it is highly unlikely that two injectors are leaking at the same time, and the failure is more or less random, meaning that sometimes it can run for a week with no problems, and then it acts up a few times either same day or within a few days

Customer :

are there two seperate igniction sensors or just one ?

gomi_otaku :

You could try swapping at least one of the cylinder injectors- like 1 and 2- to see if that is the case. There should be separate sensors for the misfire recognition for each pair of cylinders, so 1-2, and 3-4.

Customer :

Hmm, I guess you mean 1&4 and 2&3 right ?.

Customer :

The problem is worse now. I have just tried starting it 10 times in a row, and 8 out of 10 times it runs only on cylinder 1&4 for a while. But by keeping a steady RPM of between 3-4K for a short period of time it starts running on all 4 agai. Stopping and staring the car emidiatly after and the problem reappears.

gomi_otaku :

That sounds more like you have a vacuum leak- since manifold vacuum is highest at idle, and will level off at a higher RPM. If you can keep the car running at idle, listen in the engine bay for a vacuum leak hissing, and inspect all your vacuum hoses and the crankcase ventilation system

Customer :

Hi. Thanks for the suggestion.

I have tried that but have not been able to identify any leaks. I also tried spraying some medium thick sprayoil allover the manifold, but it makes no difference. But often I can make the problem dissapear by reving up the engine to 2-4KRPM for a while and suddenly it starts running on all 4. Usually it will continue to do so until stopped completly.

gomi_otaku :

I would pull the spark plugs and make sure they are not getting carboned up from the excess fuel getting burned on them. It could be that revving it clears the deposits temporarily.

Customer :

Hi. Spark plugs were changed with new 2 weeks ago :o( No change

Customer :

So I guess this is not a common fault, since it seems to be so difficult to identify ?

Customer :

Hi, Seems I have to rate your srvice by now.

Unfortunately I have to rate below OK service, as I would have expected the problem to be solved. Im not an expert but had basically already tried everything what was proposed. Perhaps I should have written all I had tried in the beginning, but was actually hoping and expecting that yoy as the expert would know just how to fix it, but perhaps this is a more difficult issue :o(

gomi_otaku :

I would pull the injectors and see what the spray pattern is like- and if they leak down when sitting overnight with normal pressure.

Customer :

Hi. It was the ECU which was defective. This has now been replaced with a new.