T5 Stalling at idle

Hm. My T5 stalls at idle on occasion, usually when in gear with the clutch in. There is no erratic idle at all, and it idles correctly all the time. It just dies. So far it has only done it when the engine is warm. It'll start up straight away no problem most of the time, although once it has refused to start for a few seconds. Aside from this, the car is running spot on. The lambda light is on but I don't have an OBDII reader. It is going into RT soon but I was just wondering what the problem is likely to be! Thanks. PS. It is a 1997 S70 T5.

Dirty throttle body or idle valve ?

Exchanged the fuel pump relay with another T5 I have, but no joy. Some hesitation when driving whilst warming up, and stalled on me a couple of times at or near idle once warm. I think I'll let RT do the biz!

Got the weekend to play with this, so I've come up with a list of things it could be. These are: Idle Control Valve / Throttle Body Dirty Camshaft Position Sensor Fuel Relay Fuel Pump Leak in a vac line Lambda Sensor MAF Swapped out the Fuel Pump Relay with a used one known to be good and still having issues - although interestingly it has 'surged' a couple of times since the new Relay has been fitted. Must be a coincedence? To recap: Problem (so far) only happens when car is warm. Has surged at a constant speed (50mph) a couple of times but not a regular occourance. It also sometimes, although again not all the time feels a bit jerky after coasting in gear for a bit and rolling back on the throttle. Engine only stalls when at or very near idle speed and so far always after sitting at idle for a minute or two. Idle speed rock solid and does not fluctuate. It is almost as if the fuel has simply been cut off and it dies. So far will start again but unless I am moving off and bringing the revs up, will die again within seconds. Classic example is crawling in 1st gear going into a garage, after being sitting idling at neutral whilst I've opened the garage door. Engine temp rises steadily to 3'o'**** position and does not variate from this once warm. So assuming this will rule out the Coolant Temp Sensor. Will disconnect the MAF later or swap out with a good working MAF. I have access to another T5 this weekend to swap bits around if need be. Any further suggestions?

Go with your first thoughts and do a clean of the Idle Control Valve / Throttle Body. Note that the moving part of the idle air valve should be 'floppy' if is stiff in any way clean with carb cleaner but be careful of using any sharp tools on it or getting the cleaner into the motor section. Also look for an induction air leak, particularly the vacuum elbow on the steering pump end of the inlet manifold. Having the code read would be a good guide, any local garage should be able to do this for you, consider buying a reader for the long term, they are quite cheap now.

Throttle switch? Perhaps not registering that you moved from idle to part open throttle?

I beg to differ - I replaced mine on my 850 and have the same layout on my V70. Also goes by name of throttle potentiometer.