Running rough when idleing

[Nathan Morrisen]

Took the s3 out today and it was fine stopped of at the garage fueled up, did another 20 miles and still ran well. Stopped for 40 mins when I made my way back home the car started to misfire when idleing or cruising but fine if I were to accelerate hard. Could this be because I have used high octane fuel? or could it be ht leads spark plugs etc

Many Thanks

[Barkychoc]

To be honest it could be one of a number of things - but don't rule out the fuel my brother used to work for a pump and tank company and water and algae in fuel tanks was more common that you'd think.

[M3CHA-MONK3Y]

Aye, you could have crap coming through the tank into the fuel filter. Harder acceleration would probably force the fuel through, whereas it could struggle on idle. Maybe a filter change.

Failing that, the usual throttle pot and AFM connections.

ETA - Possibly a weak spark, might be worth checking the coil by swapping for a known good one.

Edited by M3CHA-MONK3Y on Monday 22 March 11:37