Ok heres the problem i have a 2001 s40 and over the past few months its been suffering from rough idleing and just recently cutting out when stopped even when no rough idleing occurs. When it rough idels the revs flicker from below idle nearly stalling and then up again coniuously, the strage thing is that when i stop at the next junction it doesnt happen. It only seems to happen when the engine has warmed up and ive had a friend mechanic have a quick look at the engine and he said it looked ok so he thinks its gonna be something not really visually appparent. The car has been through a UK Mot and a service which seemed to reduce it occurance ever so slightly but im not sure. Plus a little bit of smoke/steam seems to be coming out of the exhaust not much but enough to notice in the side mirror. I have really no idea and there seems to be alot of things it could be but any help would be greatly appriciated esspecially if i can do little things to adjust it to see if it helps.

Any help will be greatly appriciated

Volvo Driver in Need. :)

Hey there,

I had the same problem a couple weeks back. There is an adjustment knob on the throttle control linkage assembly. It looks like a cone with a 10mm plastic hex on it. I'm not to sure which way to turn it, but it will tighten the throttle wire. Adjust it ever so slighty to bring your revs up at idle. Simple, yet effective. Take care.

A dodgy crankshaft speed sensor can cause this. Fuel usage will be high and in the end it will throw the engine light on but that can take some time.