Technical Uno 999cc Idle Problem

[Punto87]

My uno 45 -91 has problems with the idle and sometimes it dies and the exhaust fumes are bad high HC I think it was.
I changed almost everything that is electronical.
The lambdasensor is from an Audi but I dont know if that affects anything.
The watertemp sensor on the head is new but the watersensor on the inlet manifold is still unchanged.
All the ignition parts are changed.
The carb was changed but still no change on idle now I have a Golf mk3 carb on that fitted perfectly even with the same bolts
Soon I'm going to fit a turbo on it and I have to make it run good before I mount the turbo.

So please guys help me out make my Uno smile again

 

[Uno driver]

Vacuum advance regulator, it's located at distributor.

 

[Punto87]

I have changed that and the distrubutor
Its just revs up and down and almost dies
Sometime when I start it the battery lamp goes on but when I rev it goes away

 

[Chas Uno]

The carb was changed but still no change on idle now I have a Golf mk3 carb on that fitted perfectly even with the same bolts
Soon I'm going to fit a turbo on it and I have to make it run good before I mount the turbo.

If you have a Golf mk3 'carb' fitted then that may well be the problem. The Uno 45 is 999cc whereas I think the smallest mk3 Golf is 1300cc. The Golf carb is probably too big and is overfueling the engine.

Also you say your Uno is a '91? Is it an i.e. (SPi fuel injection model)? If it's a carburettor model then as far as I'm aware, all Golf mk3's were fuel injected so have a throttle body rather than a carb.

It sounds like you have some incompatibilities with your fuel system so first thing you need to do is fit standard parts that are known to be working. Mixing and matching parts from other manufacturers and from different engines is never a good idea.

Lastly fluctuating revs can also be symptomatic of an air leak, so check ALL gaskets and vacuum pipes as this can wreak havoc with tickover. Another option is to take the car to a garage with an exhaust gasket analyser and have the emissions checked as the results may give an idea of where the problem lies.

Good luck!

 

[Punto87]

Well sorry my english it is SPi fuel injected.
There is nothing wrong with the golf throttle body even with the original one it was going badly but the golf 1,8 throttle body is much bigger and it made the acceleration a bit better

 

[Chas Uno]

Well sorry my english it is SPi fuel injected.
There is nothing wrong with the golf throttle body even with the original one it was going badly but the golf 1,8 throttle body is much bigger and it made the acceleration a bit better

The Golf 1.8 throttle body is designed to flow much more air/ fuel than a Fiat 999 throttle body. It will also be designed to flow different amounts of fuel at tickover, which could be where your problem lies. In my experience I would say it is not suitable for the smaller Fiat engine. I can't offer any more advice based on your current setup - sorry.

 

[alexGS]

I agree with above advice - it is unlikely that the throttle body designed for a much bigger engine will work correctly at idle speed for a smaller engine (though it would possibly unleash more high-end power). For example, I wonder if the 'speed density' airflow measurement is correct with a different throttle body (the SPI has no airflow meter and thus relies on manifold vacuum measurement to determine fuel quantity injected). Even if it is correct, is the injector the original or the one from the Golf - perhaps supplying too much fuel?

I also wonder if that throttle body is designed for use with a separate IAV (Idle Air Valve) to regulate the airflow and therefore the idle speed when the throttle is closed.

I have only two suggestions: (1) Take it to a performance tuning shop who have a dynanometer (rolling road) and have the engine tuned and tested (not cheap, but possible if you change some other parts as well, I suggest perhaps other Golf parts plus a 'fuel adjuster' - also known as an 'interceptor', it allows the fuel injection pulses to be adjusted - or use a custom-made ECU (possibly expensive). I think this custom-made ECU will be needed anyway when you fit a turbocharger. Perhaps you should get on with that project - though, work out the costs first I think there are cheaper ways to performance than by turbocharging an Uno FIRE.

or (2) Re-fit the standard throttle body and use the Uno as an economical runaround while you save up for a faster car

-Alex

 

[Punto87]

I dont agree with you guys even with the original throttle body it was going this bad on idle and I tried two other uno TB's and nothing changed.

 

[alexGS]

I dont agree with you guys even with the original throttle body it was going this bad on idle and I tried two other uno TB's and nothing changed.

Fair enough. Something else must be messed up badly if changing the throttle body made no difference. Can you check the fuel pressure (or have it checked?) Maybe you have a faulty fuel pressure regulator and are overfuelling the injector. Don't forget the usual Uno throttle switch (mentioned many times on the forum, but I have not taken it apart in real life). When the throttle is closed (idle position), a black button switch causes the ECU to cut the injector duty cycle in half (for idling). Sounds like yours isn't, though I'm not completely sure on the diagnosis/adjustment.

-Alex

 

[Chas Uno]

I dont agree with you guys even with the original throttle body it was going this bad on idle and I tried two other uno TB's and nothing changed.

So what you're saying is that you tried two other Uno throttle bodies with no change, and then you fitted an oversize Golf throttle body and you still have problems? That suggests the problem lies elsewhere rather than with the throttle body itself. There's a good chance that there was nothing wrong with the original Uno throttle bodies in that case.

Also you stated:

My uno 45 -91 has problems with the idle and sometimes it dies and the exhaust fumes are bad high HC I think it was.

High HC is hydrocarbons, or in other words unburnt fuel. Unburnt fuel is down to either a faulty ignition system though the symptoms would be more like misfiring, or an over rich mixture. As mentioned above, fitting a throttle body meant for an engine with an 80% larger capacity will most probably cause an over rich mixture, which will manifest itself as high in HC readings, failed emissions and poor tickover.

Lastly, the standard 45 FIRE has a very restrictive camshaft. Unless the engine can flow more air/ fuel, fitting bigger carburettors/ throttle bodies will have little effect on overall performance. You may get a slight increase in acceleration but at the expense of fuel economy and increased emissions. An over rich fuel mixture can also cause 'bore wash' that will lead to accelerated engine wear.

Check your spark plugs. If they're black and sooty then your problem is most definitely fuel related, though it's entirely up to you whether you wish to take our advice or not.

 

[unoturbo1]

head gasket mate

do a comprestion test this happened on mine

 

[Punto87]

I doesn't disappear water from radiato and there is no oil in there but when I start the engine it can drop liquid from the exhaust a short while and it looks like water so maybe you're right

 

[EssexUno]

I'm not sure if you have stated this already, but has it been sitting for a while?

My Uno was sitting for about a year and when running it, rusty water came from the exhaust, but not anymore. And a week ago it passed it's MOT with NOTHING wrong lol. Beating the killer rust so far :slayer:

Dan

 

[Punto87]

I checked it today its water thats coming from the exhaust and not anti freeze and I think the last owner told me its not been used for a year.
But its not so much water coming out just a few drops every day I start it.
So is it just condensation or something else.