I noticed that my 2000 V40 is lacking power and I had a sudden decrease in gas mileage. I also was unable to hear the turbo spooling while driving. I ignored it for about 5 months since there were no check engine lights.

Today I finally decided to try and determine where the problem lies. I've had my mind on the Turbo for some time. I disconnect the turbo intercooler piping at the intake manifold and started the engine.The engine started with a check engine light (my guess is because no air is flowing over the MAF). I put my hand over the intercooler piping that goes into the intake manifold and had a friend rev the engine. I did not feel any air flowing whatsoever. BTW I only ran the engine for less then 60 seconds. To rule out any flaws with the intercooler piping I put everything back together and disconnected the flex tube coming out of the side of the turbo and performed the same test again with no air flow. The check engine light has cleared when I put the car back together.

I am not sure if this is a valid way to determine if the turbo and would appreciate any feedback you can provide! I heard that if I am having a problem it could be the turbo has failed or the catalytic converter may be clogged and produce similar results.