Ive got here an old Fiat punto with an idle problem, I was having a probe about today, black was on battery negative and red was on engine earth (rocker cover) as you can see in the uploaded file there are a lot of spikes, are they there because the lowpass filter is not active ?
The idle is to high and takes a long time to settle after a WOT, the temp sensor is faulty 1.6 volts @ 88c, should be 0.6v and the idle stepper is a bit sticky