Hi, I'm new to the forum.

I have a 2002 51 Seciento SX, 1108. When I bought the car in March, I was on the other side of the country, so my dad bought it for me.

He test drove it around some private land and told me it felt a lot faster than the Cinquecento that I also have. He insisted that the cambelt needed doing as he always does when he buys secondhand cars, to be on the safe side. (We didn't know it was a non-interference engine at this stage, we just knew the belt hadn't been done, it had 38,000 on the clock and we had the service history) So he took it in to Glyn Hopkin Fiat and they changed the cambelt and water pump, as they said that was leaking.

After the cambelt change my dad drove it again and it was different. Less power (After I drove it, it seemed only a little more powerful than the 899 Cinq (less than I would expect for 200ccs more) and it is idling roughly. This wasn't very pronounced however (the rough idling)

We took it back to Glyn Hopkin Fiat and one of the mechanics drove it and said 'this is completely normal for a Seicento, they always do that when idling.' To desribe it better, it sounds like it's dropping revs slightly every few seconds, and this shakes the car (you can even see the rear window shaking).


Now the car has now done around another 3000 miles and the rough idling has been getting worse all the time. I have noticed that the fuel you put in it affects this too, and it seems it gets worse when you're sitting in traffic and the engine is hotter.

Nevertheless I'm thinking the timing is out. My dad has experienced several vehicles where the timing's been out and he reckons so too.

So today, armed with a Fiat Cinquecento Haynes manual and tools, I took out the headlight, took off the expansion tank and moved it to one side, took off O/S front wheel, took out wheel arch liner, took off cambelt cover and now I'm stuck. I need to work out how to check that the cambelt isn't one tooth out, and that the timing is right.

There's a picture in the manual about lining the mark on the camshaft sprocket up with marks on the head, but my head looks completely different to the one in the manual (Prob. because it's not a Cinq Sporting like the one in the manual) and I can't seen any kind of marks at all. Furthermore I really don't know what to do next to check it's correct after lining those marks up (if I could even see any marks).

Can someone who knows please help me?

Thanks in advance

Graham

The engines in the two cars are different, although they did a 1.1 in the cinq it isnt the same as the one in a sei of your age and year

your sei is has an MPI engine which was in the sei from 2000-2004 and the cinq one or the one in the haynes is an SPI engine which was in the car from 1994 (i think)-1998 and for the sei 1998-2000

The haynes manual is pretty much useless regarding the engine as the one in the book is different, there are some obvious changes to it, whether the cambelt/timing marks etc changes i am not sure, i am assuming its different seen as you are struggling

they dont make a haynes manual for an MPI unit unfortuneatly

some people with more knowhow than me will be along shortly to probably point you in the right direction, but now you are at least aware of why you might be struggling using the book

the timing marks are in the punto faq/guides, and possibly in the cinq guides as well.

The timing marks are the same, and not specific to mpi/spi.

Kristian

There will be marks on there, and they should be in the same place. Maybe these will help (from the Sei manual).

Modern belts will also have two painted lines on them that should line up with the timing points.

Cheers

PD

If yours is the same as mine, it should still have marks on the flywheel for TDC.

If you take out the rubber plug in the gearbox bellhousing just below the thermostat, you can see a graduated toothed plate.

Put the car in 5h gear with the engine off, and gently roll the car to move the flywheel round.

Line the notch in the flywheel up with the big tooth on the plate.

The camshaft pulley marker should be pointing at the timing mark on the head if the belt's on right.

If it's almost opposite, turn the engine one complete revolution, and it should be on the right side.

The usual cock-up when doing the belt is to point the marker at the camshaft cover gasket joint, and not at the notch just below it.

You shouldn't need to jack the car up, or remove the wheel, or remove anything major other than the cambelt top cover to do this.

rallycinq said:

Modern belts will also have two painted lines on them that should line up with the timing points.

Cheers

PD

Click to expand...

Yes ! I found that out the wrong way!!!!

Ming

Thanks for all the help.

I've now checked the timing marks and it all seems to be OK. So I'll have to try to investigate what else could be causing the roughness.

However, upon putting everything back together, the car WILL NOT START.

To check that the marks on the driving pulley & engine block were aligned, I slackened the fanbelt by moving the alternator towards the front and then removed the crankshaft pulley which drives the fanbelt by removing the three bolts, leaving the pulley that drives the cambelt still attached.

When reassembling, I ensured that the 'flat spot' on the crankshaft pulley that drives the fanbelt was aligned with the TDC sensor when the engine was at TDC.

Does anyone have any thoughts? I'm rather annoyed with myself because the car was obviously working before, just rough. Now - when trying to start it sounds like a misfire, tried easy start as I thought this problem might have something to do with how many times I manually turned the engine over (was quite a few) but no joy.

Right, I've now solved that problem - it turned out that I'd put the crankshaft pulley that drives the cambelt on a third of a turn out to where it should be. I didn't see the bump on one pulley and the hole on the other. I corrected this and it now starts, but as soon as I started it the throttle now has a mind of it's own. When left alone it runs really fast. When pressed down it speeds up the engine but only slightly, until it's halfway down then it acts normally for the rest of the pedal travel. Letting the pedal go back to the top just results in the engine running fast again, much much faster than idle. If you put your foot under the pedal, and pull it up further than it should go, normal idle speed is achieved! Pull it up even further and the idle speed decreases further. If you let it go again it will then drop back down to it's resting position, and the engine will run really fast again.

It's not always the same speed it runs at when left at resting position, but it is always really fast.

It sounds to me as if the throttle potentiometer is now defective (Bear in mind I'm more electronically than mechanically minded) God knows why it's coincided with my inspection of the cambelt, if it is the potentiometer at all!

I have inspected the accelerator cable and it seems fine, it is certainly opening and closing the little flap in the top of the engine as it should do.

Does anyone know where the contacts for the potentiometer are? So I can measure the resistance manually? Or any other thoughts on what else it could be, especially if it could be to do with anything I might have disturbed or unplugged whilst looking at the cambelt!

Thanks in advance,

Graham

Check all the vacuum pipes are on in the correct positions.

Cheers

PD

Thanks rallycinq, I've now checked all the pipes I can see and they all seem to be connected firmly, I checked the two blue pipes which go to the black plastic tank in the nearside wing, and the other ends go to the top of the engine, and those pipes seem fine, and the only other vacuum pipe I could see is the black pipe going from the top of the engine to the brake servo.

If you could advise of any obvious pipes I've missed then I'll check those too.

When the accelerator cable is disconnected from the pedal, the black circular thing (I don't know it's correct name) which contains the spring and is attached to the butterfly valve seems to return further than it did before. Moving the black circular thing by hand produces the correct response in engine speed, just as if there was nothing wrong with the system, however reconnecting the pedal creates the problem again.

It seems to suggest that the spring in the black circular thing is too weak, but I am by no means experienced in these things which is why a mechanic is coming to look at it later.

There is a little screw in a bracket near to the black circular thing which seems to be an adjustment screw to limit how far the black circular thing returns to, however when the pedal is connected to the cable it never returns anywhere near the screw, even when idle speed is achieved by holding it in the correct position.

Thanks for all the help so far.

Can you back off the throttle cable so the quadrant returns to the neutral position?

Is it possible you've routed it a different way leading to the pressure on it?

Cheers

PD

That's the likely solution. I can't see it being the spring, much more likely the cable -- if these are routed so they're snagged it has the effect of holding the throttle open. See also the sticking throttle thread.

Thanks again everyone for all the responses. The problem's now solved, the mechanic looked at it, pinged the little retaining 'C' clip off of it's mounting (the cable adjustment, but I didn't know that was what it was), and then clipped it back on, and it was instantly fixed. What was better is, the rough idling has now gone too! I think the mechanic who changed the cambelt must have knocked the throttle cable, causing that clip to get stuck somehow.

Scorpione said:

Bonjour, ne parle pas Anglais !
Ces repères corresponde au point mort haut ?
= PMS ?
Merci

Click to expand...

for anyone thinkin WTF!
Hello, do not speak
English! These marks
correspond to TDC?

Scorpione said:

Bonjour, ne parle pas Anglais !
Ces repères corresponde au point mort haut ?
= PMS ?
Merci

Click to expand...

Oui!


Ralf S.