Technical Uno 1.1. i.e. Erratic Idle

[andre79ge]

Uno 1.1. i.e. erratic idle

Hello!
Iv'e got a uno with approx 100.000 miles and I have a idle problem which grow up during the last 2 years (yes, but it started very very softly).
It is evident only if external temperature is less than 10 celsius degrees and it starts as soon as engine starts to warm up (when it is cold it runs good).
If I accelerate and then I live engine at idle (or if I stop at traffic light or similar) idle cuts and then rises up, then cuts... This problem starts after a few minutes from turn up the engine (if it's cold, idle is increased by ECU) and its more and more evident as soon as external temperature is low. Sometimes it cuts out. I also noticed that if I stop the engine (with the key) and then I try to start it, it takes more times to start up respect to a total cold starting.
Lambda voltage is quite static at a low level (0.1 - 0.2 V) when at idle, can this mean a lean mixture? Despite, lambda voltage is correctly up and down during running on a street.
Vacuum advance is good (no leaks) and also sparks, plugs and similar.
However engine runs fine in all other conditions, low fuel and oil consumption etc...
What can this mean?
Let me know if you have an idea!
Thanks a lot,
Andrea.

 

[Morty Mort]

Re: Uno 1.1. i.e. erratic idle

Check if the idle speed plunger is depressed when you let your foot off the throttle. It's on the back of the throttle body. It should engage when gas is released, and halfen (?) the amount of fuel to the engine. If this is not engaged, the engine will get too much fuel when idling (when warm) and you may have problems like I did: Engine died on red lights etc.

To correct this, just loosen the throttle cable a bit.

Morten.

 

[andre79ge]

Re: Uno 1.1. i.e. erratic idle

Hello!
Idle plunger is OK, I checked it by checking its continuity with a tester: if I push or leave free accelerator, tester resistance gives different values: open circuit or short circuit (and also the cable is not tighten). So I exclude a throttle cable problem.
However I tried a very perticular stuff to resolve the problem, and it seems to be better.
I dismantled timing belt cover and I advanced cambelt (I also turned distributor in order to maintain the correct spark advance).
Infact I remember that idle problems started when I changed timing belt (work did by a technician). So I thought that timing belt substitution was not completely correct: probably the man who did the work failed a little when he regulated the position of camshaft/cambelt (by retarding a little the position of cambelt).
So I tried to rotate the cambelt and I found a better idling by advancing a little its position.
I'll let you know if this fact will produce a durable idle improvement!
I only hope to have been set timingbelt tension correctly...
I know it's NOT an easy work to do... But I tried to do it...

Sorry for my bad English, it's the better I can do...
Thank you!

 

[Morty Mort]

Re: Uno 1.1. i.e. erratic idle

The timing belt tensioner is fairly easy. Tighten the bearing (tensioner) and twist the cambelt with your fingers. It should go no more than 90 degrees. If so, loosen the bearing and tighten the belt more. Test again.

Morten.

 

[andre79ge]

Re: Uno 1.1. i.e. erratic idle

Sorry but I did not understand this procedure : I have to close tensioner, then turn cambelt? But it's not easy to turn (I can't turn it easy when it's free from timing belt, and it's impossible to turn with timing bel on!).
Could you repeat it please? Probably I have big english problems !!!
However, by advancing cambelt I resolved idling problem.
But do you think that camshaft regulation is a very critical setting? Probably it was retarded, now it could be a little advanced (I'm not sure of how much I advenced it: probably only one step, but there's the possibility that I advanced ot by two steps). Can it cause problems? I'm thinking to try to retarding it by one step in order to see differences, but it's a boring work (and delicate) and I have not a lot of time.

Let me know please what do you think,
and thank you very much, your considerations are very important for me!
Andrea.

 

[Morty Mort]

Re: Uno 1.1. i.e. erratic idle

Hei.

I´m sorry, I might have misunderstood. I thought youmment how tight the belt should be.

Morten.