Punto 2002 1.2 8V petrol, cold misfires

[DIYspanner]

One for the Fiat experts.

It only misfires when cold, all is well once its warmed up.

Any common issues on a Punto to have a look ?

The following have been replaced over the past two years due to various faults
ecu
crank sensor
coils
plugs
plug leads

 

[Burnerman]

When you try to start the car up.....
Does it start well enough, despite the misfire and is the tickover reasonably high?
The reason I'm asking is because I would initially suspect the coolant temperature sensor that feeds the ECU with the relevant information to control the cold start. There are usually two, one that works the temperature gauge and the other that feeds the ECU.
Is the yellow engine management lamp on at all?
John

 

[DIYspanner]

Thanks John

Will get the car later today to investigate - my nephew's car.

I got the message about it last night, and yes, there was mention of a warning light on.

Any idea where I find the sensor that feeds the ECU please?

 

[Burnerman]

Have the fault code read and then cleared, just in case it's a historic one - it'll soon come back if it's responsible.
I've no idea where that particular sensor is, but it will be on the cylinder head somewhere.
The coil packs are also notorious for failure but I have to say once they are dud they generally stay that way!
Best of luck with it.
John

 

[DIYspanner]

I've had a look at the car.

Took the plugs out and the strange thing is the front two are very corroded on the socket body. The electrodes seem healthy enough, its the external metal that's corroded.

Unplugged the ecu plugs to check for damp but all seemed well.

The engine does splutter for 1/2 second when the pedal is put to the floor from tick over but smooth apart from that.

I'm curious about the device in the photo. Even disconnected, the engine still runs.

 

[Burnerman]

I'd treat the engine to some new plugs in any case if they are corroded as you say.
That component is directly above the camshaft drive pulley so it could be a cam position sensor I guess but I don't know.
Can you read the fault codes? Even on an elderly car something should show up.
John

 

[DIYspanner]

Sadly, I don't have a code reader but wondering if one of the £20 offerings on ebay are worth a punt.

Regarding the plugs, it concerns me that any of the exterior metal is corroded at all.

 

[Burnerman]

An OBD2 scanner should deliver what you want.....I use Gendan stuff which cost around £500 years ago but the price has tumbled since.
I wouldn't worry about the rusty plugs, they have maybe been splashed with water draining from the bonnet or whatever. At least they weren't rusted in!
John

 

[Avocet]

My daughter has a 1.2 Punto of 2006 vintage. This may not be related but I'd best mention it just in case, because her car had all sorts of odd electrical faults and management warning lights until I found it!

The main earth cable goes from the battery negative to the gearbox, just under the slave cylinder, but it has a tag crimped on to it half way down its length, which goes to a stud on the chassis leg to act as a body earth. Despite looking absolutely perfect, the cable had corroded to almost nothing INSIDE the heat shrink insulation where the body tag was crimped on to it. I just gave it the tiniest tug and it came apart! After I'd replaced the bottom half of it with a generic earth strap from my local Halfords, it was a different car!

Also, while I remember, the main fuse box lid (on her car it's against the left hand front wing near the bonnet hinge) is difficult to fit properly (the bonnet release cable gets in the way). If not fitted correctly water gets in and causes all sorts of electrical havoc. That said, I think the 2002 model might be different?

Last thing (again, not sure of your car will have one) but my daughter's has two lambda sensors and the bottom one was loose in its fitting.

Good and friendly Punto forum here:

http://www.fiatforum.com/punto-ii/