Hi guys! In new here so im glad to be part of this forum. I have an 2001 s40 2.0T which runs pretty well, but it must have some kind of issue that i cant diagnose nor with the scan tool or any other test. The car wont past 4000rpm when its cold, when that happens the revs wont go up that limit and the engine light flashes and goes out leaving no codes whatsoever, it happens when i'm driving at the city. But when the engine is warmer the engines goes smooth as it should and revs perfect. Other simptoms that i have had are stalling after revving it high, sometimes it struggles to start, not always.
Besides that issue the car runs just fine, but im worried that the problem could be something important and i dont want to damage the engine or something.
Any of you guys have any idea what it could be, or had any similar issues? I'm all ears.
Happy christmas and a happy new year, thanks in advance guys.

 

I'd start by looking at two things - engine coolant temp sensor (plugs into the thermostat housing) - check resistance by unplugging the connector. second would be to look for exhaust leaks when cold (theory being as the system heats up the metal expands and it seals itself). If the check engine light flashes, I would expect a code to be stored so you may want to try a different OBD2 scanner

 

My bet is a bad fuel filter or some problem with the fuel pressure regulator, or possibly fuel pump. That's the kind of thing that will cause the engine to run rough after rev'ing up most often.