Hi,
Have owned a fiat uno 70 ie for a couple of years now and have had no problems until recently - basically it starts fine, idle is not to bad, some times a bit rough but when trying to drive, pressing the accelerator pedal does nothing but all of a sudden car will jerk forward and accelerate but then drop off again. It feels a bit like it is struggling to get fuel (fuel pump/filter??) of maybe it is the fuel injector control system - the problem came on quite suddenly. Maybe an ignition problem but it starts fine. Any suggestions?? Weirdly it only started happening after i took it to the garage for a warrant of fitness check. Any help would be much appreciated.

Cheers.

Hi again,
Have just noticed that it now is getting difficult to start and is idling very roughly - could it be the automatic choke, usually starts and idles at about 1000 rpm until warmed up and then idles at about 850 rpm but now idling very low even when warm, plugs were a bit sooty. Any suggestions?? please???

Cheers.

Hi again,
Having read some previous posts i am starting to suspect the ECU, are there some tests i can do to check it?

ANy suggestions?? please please pretty please.

Cheers.

richardy said:

Hi again,
Having read some previous posts i am starting to suspect the ECU, are there some tests i can do to check it?

ANy suggestions?? please please pretty please.

Cheers.

Click to expand...

"Warrant of fitness check" - aha, so are you in New Zealand too?

I suspect that not many people on this forum have experience of the 70 i.e. model. I myself can't recall if it is a single-point or multi-point injected type. If it is single-point, you may like to check for a switch on the throttle body near where the accelerator cable attaches. This switch should be closed at idle - it tells the ECU to halve the amount of fuel injected. I wonder if perhaps this switch is not closing (test with multimeter). Adjust the accelerator cable if necessary and re-test.

Meanwhile, if you have four injectors fastened into the manifold, that's a multi-point system. Usually such systems also have an auxiliary air valve that controls the idle speed. This valve has a round casing, with an electrical connection and two air hoses about the size of heater hoses, and may be attached to the cylinder head near the radiator. Sometimes the valve fails to open, which causes a low idle speed when the engine is cold. The valve is quite easy to swap for another.

I think you should check for vacuum leaks. If there is a distributor vacuum advance capsule (round diaphragm-unit on the side of the distributor), check that (clean the pipe and suck on it). There should be no airflow through the capsule. The pipe needs to be free of splits/cracks. If there is no vacuum advance capsule, then you will have a similar pipe going to the ignition ECU (Digiplex) on the firewall.

I think an ECU fault is unlikely. The Haynes Uno manual has some useful information on the resistance values of the various components of the system, e.g. the coolant temperature sensor that is a main input to the ECU. Unfortunately I don't have my Haynes manual handy to check. You can order one from Repco in NZ.

We also need to ascertain whether there is an airflow meter (AFM) or a MAP sensor fitted. A photo of the engine bay could be useful here... If there is an AFM, it's fitted in the corrugated trunking from the air filter. It's important that there are no cracks/splits in the trunking from the AFM to the engine. If there is a MAP sensor, it has a small pipe from the base of the throttle body - these are prone to filling with oil which blocks the vacuum and causes the ECU to mis-read the engine load. These are two very general injection system problems that may or may not be relevant in your case.

I'm just clutching at straws because I see that you haven't received any replies yet, so perhaps give us a bit more info to go on (year - 1991? engine - 1372cc?) and maybe a photo or two, and then we'll try to get a bit more specific

Cheers,
-Alex

Hi,
Thanks for replying Alex. Actually live in Hamilton. The vehicle is an Uno 70Sx ie, 1993, 1372 cc, with single point (mono jetronic?) injection. I thought it may have been an ECU fault based on a few other posts but i'll be more than happy if it isnt. I'll try and organise some PICs and in the meantime i will try every thing you have suggested and let you know how i get on.

Thanks for you help.

Cheers.

Hi,
Here are some pics of the engine bay, haven't had a chance to have a good look at the things you suggested yet Alex yet due to the weather.

Cheers.

richardy said:

Hi,
Here are some pics of the engine bay, haven't had a chance to have a good look at the things you suggested yet Alex yet due to the weather.

Cheers.

Click to expand...

Super!

That's wonderful that you're in Hamilton (note to foreign readers: 'city' of 120,000 people, sixth largest in NZ) - quite a coincidence.

Yes the weather has been **** recently (I typed the asterisks) and you have to wonder at what point, over the last three weeks, we stopped officially being in 'drought' conditions.

Next week I am mostly free, so you should send me a private message and arrange to pop over some time (I'm on the east side of town, Fairview Downs area, between Ruakura and Chartwell.)

Anyway the photos answer most of the questions - your distributor doesn't have vacuum advance (it's on the end of the camshaft), the Marelli Digiplex unit is behind the battery (and will have a vacuum hose), and there is some odd stepper motor gizmo that pushes on the throttle - my bet is that it might be seized. Or, that's the switch I was talking about.

Hopefully someone might chime in with some advice before we have a look at it together next week

Cheers,
-Alex

Hi Alex,
I actually live on the east side of town as well - over by the varsity. Well things have deteriorated somewhat, now doesnt start or very difficult to start and wont idle. Have done electrical tests of sensors to check they are in spec with what haynes manual says only question marks seem to be over idle check switch and throttle position switch. Have checked vacuum lines and seem OK. PLugs seem to have good spark and coil checks out OK. Engine speed/TDC switch also checks out OK as does coolant switch. The idle check switch has a some sort of stepper motor in that is working but hard to tell if working correctly. Couldnt find any check info in haynes for throttle position switch which seems to be a combination of a potentiometer to give feedback on position and also a switch to give feedback on when butterfly valve is closed.

Any further ideas?

I may have to bite the bullet and take it to a garage (even though its probably something simple), should i take it to a specialized Fiat agent or can you suggest someone - assuming i can get it going.

Cheers,

Richard.

Hi Alex,
i found the problem - and its not good news. Basically the ECU was full of water!! Still havent discovered where it had come from but there is a fair bit of corrosion on the board itself. Although i am an electronics technician - i think its probably to far gone and will need to be replaced. Can second had units be used? Or are they "keyed" to the vehicle. I also assume that they are not cheap to get new.

Cheers.

richardy said:

Hi Alex,
i found the problem - and its not good news. Basically the ECU was full of water!! Still havent discovered where it had come from but there is a fair bit of corrosion on the board itself. Although i am an electronics technician - i think its probably to far gone and will need to be replaced. Can second had units be used? Or are they "keyed" to the vehicle. I also assume that they are not cheap to get new.

Cheers.

Click to expand...

I was an electronics technician once, too...

Those Digiplex units are not 'keyed' or coded to the vehicle, and may well be the same as the ones used on the Tipo. Being Digiplex 2, it can't be all that different to the Uno Turbo Mk2 either.

Next I would suggest Mal Simmonds at www.fiatparts.co.nz (phone 827 8918).

Good luck with it anyway - I presume you have tried just cleaning the board with contact cleaner and drying it out?

I fixed a similar problem with my Alfa 166's body control module - it had a small amount of water trapped under the connectors and had corroded a couple of the vias - so by adding some wire-wrap wire (stripped and soldered) to the underside, I was able to fix it. A little while with an LED torch and a multimeter was all it took to trace the double-sided board.

During the week I can come and take a look, if you haven't got it going by then.

-Alex

Hi Alex,
Was actually the fuel injection ECU. It looks like water got into the wiring conduit in the engine bay then traveled down the conduit to the ECU plug in the car under the dash then up into the ECU electronics itself as well as on to the carpet etc. Very odd. Will take it to work tomorrow to see if i can resurrect it. One of the connector pins that goes from the plug to the board has completely corroded away so i might have to get a bit creative with it.

Cheers.