2.0TS irregular idle, 'hunting'.
As this sounds like N-other number of similar questions I'll start by saying I've done a bit of searching and not been able to find a match for these symptoms.
Our 147 TS ('06) has developed an irritatingly lumpy idle which I've been attempting to find a cause for for some time. It doesn't 'rev', you'd hardly see the tacho needle move and it's not that obvious to the ear. It's most obvious when sitting in the car, especially when cold, at junctions or lights what I can best describe as a throbbing (not the nice kind)! It does seem to diminish when properly up to temp. There's no warning light and no stored codes. I've looked at a number of parameters with alfadiag which generally seem 'normal' except
for the ignition timing which is very irratic. Disconnecting the airflow meter makes no difference. I've had the plugs out - they seemed ok to me and gapping them has also made no difference.
I would love to hear from anyone who's ever suffered similar or who might think of something I haven't. I did once hear a mention of split inlet manifolds but I haven't yet gone to the trouble of pulling it off which isn't trivial (well not outside in winter anyway!). I have tried disconnecting the battery for a long period and also tried the 90sec on/off to no avail. The variator is basically silent, though that doesn't necessarily prove anything.
Doesn't say that in the manual