My S40 has been garaged for ten years with a blown turbo. My son sourced a second hand t4 turbo and installed in the car. The car has almost no power. I can drive it around at 20km/hr but struggled to go up a small hill or even get up the car ramps. The catalytic converter got so hot the the carpet etc in the car started smoking and melting. There are no errors on the OBD/ECU. (I did have coil/misfire errors but the plastic plugs were not seating properly to the coils and I fixed that and reset ECU. I'm not a mechanic but am happy to give anything a go. There was no boost showing up on OBD and I couldn't hear the turbo spool.I checked the 'new' turbo and it was shot so I rebuilt it and put it back in car. Turbo now spools and get boost on OBD but car symptoms are the same. No power, overheating Cat (I didn't let it get too hot but my inexperienced eye tells me it's getting too hot too quick - can't hold finger on interior floor of car). I am supprised that I am getting no errors on the OBD. Any ideas what I should attack first? What could be wrong that wouldn't cause an ECU error? I also did the PCB system while I was under the bonnet. Not sure if it's normal for this car but it splashes a lot of oil out if you open the oil cap while running. I don't get that on my 2.5T but that does have some angled flanges under the cap that look like they are there to stop oil splashing. Any advice appreciated. Want to get the car back on the road for my son. Thanks