Technical Cinquecento Rough Idle

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Technical Cinquecento Rough Idle

BigStoo

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Hell everyone. I'm new here.

I've just bought a '96 Cinquecento sporting.

When I bought it, it ran lovely. Later that same day, though, it started to idle rather roughly, almost as though it's misfiring. It start first time, though.

One possiblity is that when I went to pick it up, it was out of fuel. The guy filled it up with fuel from his lawnmower. Could it be that some c**p from that fuel has got into either the fuel filter or injectors? Would that give these symptoms.

Strangely, though, it doesn't seem to be down on power. It'll rev right through the range, and it was still pulling nicely at 80mph in 5th (on a private road, you understand).

One other thing to note is there is a definate petrol smell when you start it, like it's flooded. But that would mean too much fuel is getting in, not too little, right?

Where to start? A day in. I don't want a pup. :(
 
Hi welcome to forum

Petrol smell - yea too rich.

The injectors are always under pressure and can leak too much fuel even when stationary, cheack the oil level and if it is above the full mark change it first, i.e. now.

If it seems thin or smells strange (it wont necessarily smell off petrol), change it first.

The injectors shoul survive crud in tank for some while although it is not desirable, the filter will clog. the cat wont survive any leaded petrol.

The car probably needs a service, and should not be run dry, that can also damage the cat, the hand book says, when the warning light comes on fill it up immediately.

In the mean time try injector gum solvent in petrol tank e.g. redex, go for max dose initially. Monitor the oil level carefully the oil stops being oil after it gets too much petrol main and big end bearings are expensive to grind & replace.

If it does not stop missfiring or gets worse you probably have a different problem or will have to pull the injector(s), and leave overnight in neat redex.

The good news is the car probably has not been used for a while and the petrol lines merely had some gum residue in them, but could be something else...

Sorry

Noel
 
Oil was waaay too low actually.

I'm just topping it up, checking plugs, leads etc. Stay tuned...

I wonder if you could answer this...
There is a small tube, perhaps only 1mm coming off the air intake. There is also a small tube of similar size going into something with a connector near what I assume to be the ECU. If I blow into this tube, the idle engine note changes. If I take the connector off, the engine light comes on on the dash.
Should those two tubes be connected? Sorry if that's a bit vague.
 
Think that's the tube that should be connected to the map sensor close to the ECU.

And that should connects to the inlet manifold, and yes they have to be connected. And i think that is your problem :)

Ming
 
Right. Ive found more pipes and more holes. They all seem to be a similar bore and I'm not sure which is supposed to be going to which. I think I might have pulled one off when I was adjusting the clutch. Thinking about it, the idle problem started pretty much then.

I'll try and take some photos, but in the meantime I'll try and describe where they are.

The is one pipe coming from the air intake, just as it turns a corner. The pipe is maybe 1mm.

There is another pipe coming from something above the ECU (MAP?). It is slightly larger in diameter and has a larger rubber connector on the end.

I've just taken the airbox off and there is a hole a pipe should be plugged into underneath. It looks like it's connected to a red sensor inside the airbox. Am I right in the thinking that the pipe from air intake should be connected to that? It's exactly the right size.

So that leaves me with the pipe from the (MAP?) sensor going nowhere, and I assume that's why I have a rough idle. So, the million dollar question - where should it be connected to?
 
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If you only have one disconnected pipe you need a flash light and a small mirror to search so the small spigot that is clean and about the correct distance, and is missing its hose, the only problem is if you find two, but this is unlikely.

Noel
 
OK, so here's a couple of pictures.

The first one shows the pipe that's not connected to anything. I've laid it on top of the airbox for clarity. Where should it go?

The second pic is the underside of the airbox. The pipe entering from the left is coming from air intake. The one from the right is going to the back of the TB (to the MAP sensor take-off according to the guide I think).
 

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It's fixed!!!

Thanks for pointing me in the right direction.
It was indeed the MAP sensor (as you can clearly see from the above picture). I did some searching and found a picture of the general area I should have been looking. It took the ECU maybe 10 seconds to settle down once I'd reconnected it, now it's hunkydory.

Now I've just got to change the rocker cover gasket. What do Fiat make their gaskets out of? Cheese?
 
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