Hi, my first post,
I have a 2001 black top se 1.6 focus petrol
i am experiencing a subtle stutter at idle

the rpm needle seems relatively level but it stutters and makes a slight resonating/wobbling noise; only at warm with the a/c off, if i turn a/c on it goes away when under load...

it idles at 700/800rpm when warm. there are no DTC in dash stored.
the vacuum hose was replaced as found to be split behind manifold, i run it on v power fuel with an aftermarket induction kit but it was doing this before changing the air filter..

the plugs are dry and clean, and it has not got the maf sensor, just a map sensor.

it's not perfomance hindering but irritating and relatively noisey when idling

no other symptoms!! the only thing i'm yet to do is an ECU reset. any suggestions please? (sorry if i have not posted this in the correct section entirely.. but i have searched high and low and cannot find anything like this on the internet)

thanks in advance

 

update: to explain the noise is a light popping noise through the air filter which some people have experienced already.... however... new genuine plugs and a OE equivalent of leads has cured the problem!

-an ECU fuel/air trim reset has also been carried out through removing the battery for half an hour.. seems to have worked a treat. hope this helps those for future reference.