I have a 2nd car, a '99 Corsa 1.2 16V as a little run around to teach my wife to drive.
Problem 1
The ECU light came on once or twice under load and I could hear detonating. The mechaninc replaced the, and I quote, "Air Mass". Nice. That solved the ECU light and det.
Problem 2
Hunt Idling. Intermittent issue, when stationery the car goes from 800'ish up to 2000rpm and back down repetitively. I told the mechanic about it on the first meeting, but he seems to not remember this and is now saying it's a new issue. I had a look through the car history (it was my wifes mums car since new and all receipts from the same garage have been kept). He's now replaced the "Mass Air" twice and apparently changed the "Idle Control Valve" before as well, but swears hand on heart that this car has never had idling issues?? hmmmmmmmmm....
I told him that when I'm gearing down and slowing on approach to a traffic light the car actually still accelerates due to the revs going up. He said this is normal. I know it's not.
Any clues on how to troubleshoot hunt idling would be a great help so I can sort this out without ever having to speak to this man again.
Cheers
Mark