Technical Seicento 2002 stuttering

[Seamus2012]

Thanks for that. Got it sorted now. Found that one of the wires in the VAG plug had disconnected.

I have run the Multiecuscan and am no further forward.

Cleared the codes and no further ones came up.

Went through all the parameters but can't tell if they are normal or now. On the lamda sensor pre cat at idle it switching from lean to rich continually. Managed to capture a screen shot of the first page of the parameters.

Whilst testing I found that once the fan cuts in (ie its hot) then it runs rough and stalls, and is difficult to start again until it has cooled down.

Can someone guide me as to where I go from here please.

 

[glenn2602]

Seamus, try removing and cleaning the stepper motor. The Cinquecento has one on the fuel body, held in place by 2 screws and has an electrical connector .. I'm guessing your car does too? I believe they also be known as air bypass/idle valves .. something along those lines.

There's a link below that may be informative (it's not a Fiat..)

http://www.gomog.com/allmorgan/StepperMotor.htm

 

[Seamus2012]

Thanks I will check that out tomorrow.

I the meantime I have managed to get the rest of the data from Muliecuscan but have no idea if the readings are correct on not. Any advice please.

 

[glenn2602]

Sorry, Seamus .. that's all Greek to me.

 

[Seamus2012]

I am in the same position - they are mostly meaningless.

I have had no experience with petrol fuel injection and am totally lost with this problem.

I have had another look around today.

I noticed the bottom of the choke tube is wet - I am guessing that this is from the exhaust recirculation.

I found that when I disconnected what I think is the stepper motor (I could feel it reset itself when the engine was turned off) that it ran smoother. This was once the engine was running.

Not sure how the stepper motor mounts. Pictures I have seen show it flange mounted but this one does not to be so mounted.

I am enclosing a pic of the engine with various items marked Could someone check that I have correctly identified them please.

A is TPS?
B is Stepper motor?
C is Map sensor
D no idea what this is

Thanks

 

[jackwhoo]

Post the fault codes the car was showing
That's the fault finding starting point. Not the data already posted.

 

[Seamus2012]

Thanks

The data that was there was because I had unplugged various sensors. Since clearing those no other turn up but will check again

 

[Seamus2012]

I have connected up the scanner again and cleared the faults I had created by unplugging various sensors.

Had the car running for about 1/2 hour and no further errors appear although it is obvious that there must be one somewhere. What I did notice was that the "Canister Fill" parameter was showing between 0.002% to 0.004% most of the type but when it stalled that reading went down to 0. Don't know if that if relevant. The tank is around 1/4 full.

What readings are relevant to this problem?

 

[glenn2602]

Try driving your car with the fuel cap undone. If the stuttering disappears this may indicate a vacuum problem/error

 

[Seamus2012]

Thanks - I was thinking that so gave it a try but no good.

This is so frustrating - might have to do a Basil.

I am guessing that since no faults are shown up that there is nothing wrong with the sensors.

It does seem to me that it is some sort of fuel problem/starvation but just where I don't know.

 

[glenn2602]

I agree, it does seem to be a fuel/air problem.

I have a 900 cc Cinquecento which since I've owned it - 18 months - has had that red 'fuel spray' warning light on the dashboard. Admittedly, the car has only done 200 miles since I've owned it, and it was jerking and spluttering - which a new MAP cured.

But .. that warning light is always on and the car doesn't better more than 28mpg. I've changed the lambda sensor, thermostat, coolant temperature sensors etc etc ..

Almost a year ago on its MOT I asked the workshop if they would have a look at it when they were mot'ing it. They thought it was a gasket problem and £80 later I knew it wasn't a gasket problem ..

They did a diagnostic test and discovered an 'open circuit' error message. They didn't know what that meant or what caused it, but said it probably would be an easy fix if I visited an auto electrician .. which I did ..

.. and the auto electrician connected his laptop and didn't know what the problem was, though he said it probably would be 'something simple' .. Yes, I'm sure.

At the moment I'm putting the cylinder head back on ... somehow, some alloy found its way into a couple of bores and battered the spark plugs. I have no idea where the alloy came from or how it got there ..

But, as I work (slowly) I'm also stripping the injection unit down and inspecting/cleaning as I go. The injector - well, it looks fine, but how do you tell? I've sprayed wd40 inside the injector gauze. I've removed the fuel pressure regulator - basically it's just a diaphragm with a spring/pin underneath .. so maybe check yours, too ...

I've cleaned the stepper motor - the air valve - and seeing that they're only a tenner on Ebay, I've ordered one. Maybe the old stepper motor 'works but doesn't work'..

I have no doubt that when the cylinder head job is finished and everything connected up that that warning light will still be lit up. I can feel it in my bones. So .. what then .. new injector? New CPS just to 'check' .. or undo the fuel cap and strike a match?

There's no alternative but to keep trying different things ... and .. just to throw a spanner in the works..

... I once had a VW golf that idled brilliantly. At speed it would often cut out - and the cut-outs became increasingly frequent, but would restart almost immediately... the fault was the electric fuel pump.

Sorry to spoil your day, but you'll get there in the end

 

[glenn2602]

Tempted...?
http://www.ebay.co.uk/sch/i.html?_f...el+pump.TRS0&_nkw=seicento+fuel+pump&_sacat=0

 

[Seamus2012]

Thanks for the support and sorry you having troubles.

It is so easy for garages to replace this that and the other and you end up with big bill and the problem remains.

It is my Wife's car and she can't drive much at the moment so no real panic and can afford to take my time but it is really bugging me.

I have been searching this forum and it might be the fuel filter but there are differing opinions as to whether this car has and where it might be fitted. Thought it might be in front of the o/s rear wheel but can't see anything after a quick look.

The thing is that initially it has a lot of power for a couple of miles and then looses power.

 

[Seamus2012]

Tempted...?
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR1.TRC0.A0.H0.Xseicento+fuel+pump.TRS0&_nkw=seicento+fuel+pump&_sacat=0

Sure it is not that. I uncovered the pump above the tank and disconnected the outlet hose and put a temp hose into a 1lb jar. It filled with gusto so sure that is not the problem.

 

[jackwhoo]

You would be much better served to put the return fuel line into a large container run the pump for an extended time and make sure there is no reduction in flow.
Fuel injection requires pressure to work not just flow volume.

 

[glenn2602]

Yes, Seamus .. it may fill a jar easily at idle speed, but sometimes the pump may 'stick' and not supply enough pressure for acceleration and higher speeds. The pump may not be supplying pressure across the board or under different loads.

In-tank fuel pumps actually do quite a lot of work and wear out. That's all makes of cars .. Some cars have two fuel pumps - the 'lifter' in the tank (which does all the hard work) and a 'pusher' pump in-line.

You can get a fuel pump pressure tested - that's done by disconnecting then fuel line and fitting a gauge. However, that only gives a reading of the there and then. A 'marginal' fuel pump - one that is on its way out may be ok at 1pm, but at 1.30pm it can be a different story.

The thumbnail image ...
and the link:
http://www.ebay.co.uk/gds/5-Common-Symptoms-of-a-Malfunctioning-Fuel-Pump-/10000000177634796/g.html

I agree that it could be a fuel filter .. but ... I think it unlikely. Usually with a blocked fuel filter the car will run okay for a mile or so then slow down ... pulling over and waiting a minute allows enough fuel to get through the blocked filter and you can get underway again. Most fuel filter blockages were caused by rust from inside the fuel tank.

The 2nd thumbnail is of a fuel filter. Ebay lists one for the Seicento. Your fuel filter will more than likely be attached to the underside of the car, midway between the tank and the engine.

Yes, workshops will replace parts just in the same way you or I would. Sometimes it's guessology with crossed fingers, but that's how it is.

 

[Seamus2012]

Thanks to you both - you make good points. I will give it a fuel flow test tomorrow. I have a spare gallon can I can use. Will try it after it has been idling for a while and is stalling.

On the fuel filter. I can see the hoses coming down from the top of the tank and they then disappear into the sill and probably use that route to the engine bay.

Where they enter the sill there is some sort of connector on both hoses just before. Would have thought they would have had a continuous run. Is this standard?

 

[glenn2602]

Not sure why hoses would enter a sill. Usually a fuel filter is bolted where it can be seen and accessed and the fuel line is a direct run up to the engine compartment. Maybe the connectors you see are where the fuel filter disconnects from the main run?

I think you're wasting your time pumping fuel into a gallon can. There's no load on the engine and the fuel pump is likely to pump away merrily all day long. You're not measuring pressure and besides, a failing and erratic fuel pump may work- not work -work-not work - whenever the fancy takes it.

You've done a fair bit to that car - maybe now is the time to just fit a new pump. It'll either put things right - and if it doesn't .. you've ruled out the fuel pump.

 

[jackwhoo]

If you measure the return flow it's after the pressure regulator so the pump is having to pressurise fuel , the fuel then depressurises and returns to tank.
The return flow should be equal to the feed pressurised flow.
Do also check the pressure regulator diaphragm and spring too. If they are iffy there is no validity to checking return flow . Because system will not be at correct pressure or any pressure . This will cause bad running too.

 

[jackwhoo]

Obviously if return flow is poor it points to filter or pump or both.