Technical MK1 Punto Idle Revving / High Idle

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Technical MK1 Punto Idle Revving / High Idle

This afternoon I could tested it driving. And it feels awesome! The acceleration is soooo smooth, before it was rude, not linear. Now is so pleasant. Idle is perfect, it didn't hold at 2000 or any other revs, always going down to idle when shifthing gear. So idle issue finally solved!

I am so glad, reading your thread and getting to the part where you manage to fix your lovely car. Congratulations!
Can you please help me, as I'm not sure if I get it right. Was changing the O2 sensor the fix for your high rev idle? I am having the same issue with bad idle on my Punto, engine revs between 1500-2200 RPM more or less, and it does it totally random. One thing is for sure, on cold start it runs nice, when it gets hot the problem starts. Started a little time ago, at first was now and then, now it only runs as it should now and then, most of the time, when engine is hot, I do hav this high rev on idle problem, surging I think it's called.
My thread is here:
https://www.fiatforum.com/punto-ii/488092-engine-revs-2000-rpm-idle-2.html
Thank you!
 
Majobusa has done a great job in being thorough and methodical to resolve his issues, and Jackwhoo has been brilliant in his support. Both of you are a credit to the forum,
Without wishing to detract from your skills, may I add a little bit that might help others.
According to my workshop manual, if the battery is disconnected the ECU requires to be reset. This is done by taking the car for a drive to relearn the settings. Otherwise, according to the book, it may cause uneven idling. I think it is a point worth being aware of.
Mind you, I still needed a Lambda and Cat for its last MOT. The good news is that it is due it's next one and has only done 3 miles since the last, so fingers crossed.
 
I am so glad, reading your thread and getting to the part where you manage to fix your lovely car. Congratulations!
Can you please help me, as I'm not sure if I get it right. Was changing the O2 sensor the fix for your high rev idle? I am having the same issue with bad idle on my Punto, engine revs between 1500-2200 RPM more or less, and it does it totally random. One thing is for sure, on cold start it runs nice, when it gets hot the problem starts. Started a little time ago, at first was now and then, now it only runs as it should now and then, most of the time, when engine is hot, I do hav this high rev on idle problem, surging I think it's called.
My thread is here:
https://www.fiatforum.com/punto-ii/488092-engine-revs-2000-rpm-idle-2.html
Thank you!

I've read your post and it's fair to say you did a very good job so far.

In my case it was the lambda sensor. I only have one sensor right after the exhaust manifold, it doesn't have a second one before the cat.

Also the barometric pressure sensor made a difference.

By the way, this month has successfully passed the MOT
 
Floating the thread because I have more to share with you guys.

After solving the issue with idle, it came back... again!

lately the car was not running fine at all. The accelerator got stuck from time to time making the driving annoying. Also, and to me it looked related to, the idle went up to 2000 rpm randomly. Specially when driving smoothly. So I reviewed the throttle body. It seemed clean but I cleaned it anyway with an intake cleaner in spray because at closed position it got like glued and resistant to opening (same as what I felt in the pedal). It got better but just for few days. So I decided to replace the throttle body with one I had at home from scrapyard that to the touch it felt much much better. During the exchange I reviewed the seals, and you know what? The one below (number 14 of the picture attached) was partially destroyed and gone. Most probably this was impacting in the idle issue as well. That pack of seals costs around 60€ (50£) at dealer, so I bought seal paper in Amazon and made it by hand. With both mounted, the new seal and the "new" throttle body, the car runs perfect! Like new, I can't be more satisfied with the result.

Just wanted to leave it here in case it helps anyone else
 

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