Huntind idle

[porschedavid]

1984 Porsche 911 3.2 carrera
When first start car, For the first 1 to 2 minutes the idle hunts up and down.After 2 minutes it idles right,any ideas

[darrin]

Lots of threads on this issue, surge generally caused by mixture being too rich - see, e.g. Surging idle at cold start up

[porschedavid]

1984 Porsche 911 3.2
Been having trouble with idle hunting.
Today took car for mot,Failed on high emissions. Co 12.5, Max 4.5.
If i take oil cap off hunting stops and emissions are good at Co .5.
Undone screw on air flow meter anti clock wise but still hunts on idle.
In my paper work it shows it had a air flow meter 3000 miles ago but that was in 2006, I assume it was new air flow meter it cost £198.18,Anyone any idea what to do next

[darrin]

the threads I linked to generally suggest (and provide procedure for) setting the mixture correctly -- your observation that taking the oil cap off fixes your problem seems to support this as the probable cause of your issue (hunting idle caused by a rich mixture and opening the oil cap lets more air into the mix that leans out your mixture). Check out the threads I linked to above (the link's underlined in blue) and see if that gets you anywhere.

Also, while the air flow meters can get worn, there are a lot of posts on how to reindex the "barn door" vane to fix -- see, e.g. [3.2 Motronic] Air Flow Meter wiper arm re-tracked - WOW!

I'd start with confirming that your mixture is properly set and going from there

[porschedavid]

Anyone else ?