Technical Very Rough Idle Uno 1.5 Selecta

[Renier24]

Dear everybody,

Sorry but I did look everywhere and I haven't been able to find anything specific yet. My Uno 1.5 Selecta from 1991 idles very roughly, especially when the engine is warmed up, and in stop and go traffic it's just the worse.. I'd say it's like a rodeo where it just slows down rapidly at once and then pulls steadily the next moment and so on.

I've sprayed brake cleaner over the injection parts and the intake manifold, not too much because I didn't want to damage any plastics or rubbers, but it did not change the idle at all so I don't think it's an air leak. Also when I pull the throttle cable a bit to throttle up somewhat it runs roughly just as well, so it's not just running at a too low idle I'd think.

What should be the first things I could check? Anybody ever experienced or heard about anything like this before and a potential solution?

Many thanks in advance either way!

 

[johorridoh]

I had this on mine too. A FIAT mechanic told me it´s the worn butterfly valve potentiometer It´s that black plate on the side of the SPI.
Get a working used one. The part , if available, cost about 400 €
I replaced it an the car was running perfect again.

 

[Renier24]

Many thanks, I'll look for it! I've already replaced my spark plugs and my fuel filter, spark plugs were damned white.. long overdue!

 

[johorridoh]

A regular service, does pay off

 

[Renier24]

Turns out it came down to the part which has the injector and a temperature sensor on it, because as we opened the air filter housing we noticed it had a very strange pattern in the injection, replaced it with another used one a very helpful guy still had lying around and the problem was pretty much solved! How great

 

[Lucoudev]

Yeah, and it would be nice if you payed for your parts. You know exactly what im talking about.