I still claim missing spark / shot coil (one of them).

The small vacuum lines black and brown, these should have nothing to do with the problem at hand. This two nipples I believe have some sort of thermo swich on the inside of the air box, and it controls the flap that lets in the hot air from the vicinity of the exhaust manifold into the inlet. The sole purpose of this whole contraption is to speed up engine warming up.

! But then on the other hand, if you have a problem with this, and your engine sucks in very hot air when warmed up, this could be it! The IAT sensor has range until 120 degrees or so, after that it would trigger an ECU fault, an ambient temperature of ~20 degrees is assumed, and this can screw up fuelling. Note that this does not mean that the IAT sensor is shot in any way.

This is easy to check, take off the air connector on the right hand side of the air box to get the air directly to the box bypassing the whole theromostatic contraption and see if that helps.

rallycinq said:

What did the engine temp sensor read at that point?

D

Click to expand...

You're talking ohm resistance now?
We didn't measure. It's a pity I don't live where the car is parked so we'll have to try that later. The sensor is brand new though, for what it's worth.

woj said:

I still claim missing spark / shot coil (one of them).

Click to expand...

But why only when warm then? Is that logical?

The small vacuum lines black and brown, these should have nothing to do with the problem at hand. This two nipples I believe have some sort of thermo swich on the inside of the air box, and it controls the flap that lets in the hot air from the vicinity of the exhaust manifold into the inlet. The sole purpose of this whole contraption is to speed up engine warming up.

Click to expand...

Allright. Thanks!

! But then on the other hand, if you have a problem with this, and your engine sucks in very hot air when warmed up, this could be it! The IAT sensor has range until 120 degrees or so, after that it would trigger an ECU fault, an ambient temperature of ~20 degrees is assumed, and this can screw up fuelling. Note that this does not mean that the IAT sensor is shot in any way.

This is easy to check, take off the air connector on the right hand side of the air box to get the air directly to the box bypassing the whole theromostatic contraption and see if that helps.

Click to expand...

Worth a try. Altough the temperature seems to be fine, it just 'triggers' something.

There are 4 temperature senders.

1) IAT, in the throttle body
2) Engine water temp, in back of inlet manifold, two pole
3) Temp gauge sender, in head, single pole
4) Fan switch, in radiator.

The two tubes on the air box. The correct position of these is important as one of them operates the flap. Wrong way round and the idle speed goes to 1500 rpm, as you've found.

There should be no connection between the rough running and the fan not running, as above, they use different sensors. That bit makes no sense.

Just to rule out a coil, run the engine up to the point it starts misbehaving then remove one coil lead (and replace it) one at a time.

If you get to the point where the engine note doesn't change, that one is not firing and will require investigation, although each coil fires two plugs so you would expect it to run on two, not three. Could be a plug breaking down, or a lead, but I still don't get why the fan won't come on...

Cheers

D

Doesn't the engine run cooler when on two cylinders?

rallycinq said:

There are 4 temperature senders.

1) IAT, in the throttle body
2) Engine water temp, in back of inlet manifold, two pole
3) Temp gauge sender, in head, single pole
4) Fan switch, in radiator.

Click to expand...

So I'm wondering...

What's this? Looks like an NTC (temperature sensitive) transistor. Any idea?

So number 2 and 3 are replaced. Number 4 seems to work flawlessly.
Number 1, where is that exactly? I've seen so many connectors and sensors and wires that I can't remember that one really.

The two tubes on the air box. The correct position of these is important as one of them operates the flap. Wrong way round and the idle speed goes to 1500 rpm, as you've found.

Click to expand...

Weird. It didn't do 1500. We changed them around (so they now match the inscription saying 'brown') and nothing really changed.

There should be no connection between the rough running and the fan not running, as above, they use different sensors. That bit makes no sense.

Click to expand...

Clear.

Just to rule out a coil, run the engine up to the point it starts misbehaving then remove one coil lead (and replace it) one at a time.

Click to expand...

Easy does it, we will do that one.
I know how a car running on two or three (one even, had a Visa 2 cylinder at some point ) coils sounds and I don't think that's it. But there's no harm in trying.

If you get to the point where the engine note doesn't change, that one is not firing and will require investigation, although each coil fires two plugs so you would expect it to run on two, not three. Could be a plug breaking down, or a lead, but I still don't get why the fan won't come on...

Click to expand...

Well it does come on nicely as long as the car runs good.
As soon as it starts going into something we Dutch call 'emergency run' (I'm sure there's an English therm for that) it just doesn't exceed 80 degrees, fan or no fan. So I just think the fan won't turn on then. I still think though that when stationary and idling for a long time, the car should heat up, even when running as badly as it does. It just seems as though it doesn't though...

Oh, update! Apparently my dad already tried that without telling me.
Whichever coil you unplug it will run way, way worse. It is running on all four cylinders.

Sensor 1, IAT, is what the red arrow points to

Allright, got news!
It's typical for my dad to go 'good enough'. This time too apparently .
He disconnected two wires from one coil... Car stopped working so he figured 'must not be it'. Not sure how this worked in his brain but we disconnected two wires from the OTHER coil and everything stayed exactly the same.

So here you go, a 2 cylinder cinquecento.
Question now is... Coil or ECU?

What did I say And injector light means the diagnostics software would tell you this in 2 minutes.

This is IAW 16F, I have never seen one or heard of one broken. If you want to be sure it is not the ECU swap the coils and do the same test.

Haha, you did! It got a bit lost in translation though. I speak English on a daily basis. One of my girlfriends (modern relationship, blahblah) is French and doesn't speak Dutch so usually it isn't a problem. But when it comes to technical, non-audio related English I sometimes confuse stuff. I somehow thought at first that by coil you meant spark-plug. Not sure how as I very well know what a sparkplug is.

Anyway, we exchanged them and the car won't run on the other coil, it doesn't even try to start. So even though there may be a reason that coil is broken, it most surely is! Combine that with the knowledge that these coils overheat regularly because of their location and it's definitely a logical culprit.

The parts store had just closed when we found out. I'm going there first thing this Monday to see if they have one for me. I can order it online and it's not that expensive but it'll take some time to get here. Since it's a very generic coil I hope they have it in stock already. We'll see!

Also I'd like to add, and this is meant for everyone, that I'm blown away with the input I get here. You really try to help someone and think along. Responses are swift. It's brilliant. This is really what a forum should be about. No arrogance, sensible replies (even to questionable questions ) and a lot of friendliness. It's time I move to the UK

I'll be back next monday!

Edit: Oh, or Sweden. Well... I have always had a thing for the UK and Scandinavia. And Canada. I am about to find out whether I'm right about that coming winter .

I am not Swedish, and I started my Fiat adventure in NL actually Lived there for 10 years until last year. But I am not Dutch either.

To the subject - a coil from any 8V FIRE Fiat will do, can be from scraps too. That's what I did when one of mine died in a huge water splash accident. The engine lived happily ever after.

A coil sets me back 30 euro's, I figured I wouldn't bother getting a second hand one for that kind of money, especially since they seem to die quite often in these cars. You don't want to replace one with another one that's close to dying.

So where are you from then?

I also believe that some alfas use the same coils. Pity you aren't in UK as I have loads of coils here I could send but think postage wouldn't make it viable

That's really nice of you!
If I had the money I'd be in the UK monthly .

Nevertheless...
UPDATE!
Apparently Heuts (car shop) is opened on a Sunday.
I couldn't say at my parents after I delivered the coil there, unfortunately but my dad put the new coil in the car. Let it run to 90 degrees c, drove it for a bit, flawless. He couldn't drive it very far as he's got very bad eyesight but so far so good.
Tomorrow I'll take the Citroën BX that's at my driveway right now to my parents and leave it there and take the Cinquecento back. My father is coming over to my place to do some work on my house. If it the car takes him and me here and back to my parents place I have faith that it might work for some time.
More tomorrow!

So far so good! It has its occasional hiccups every now and then but otherwise it's smooth sailing. Perhaps the other coil is on its way out too. Probably just leftover crap from running rich.
I am going to drive it for a week or two and see how it behaves.

Next question; I only have the red key. What's the wise thing to do? I know I should use a blue one.