VIS valve
 

My 2.5 v6 has an annoying 'flat-spot' when accellerating at just under 3000rpm. Once over this point she pulls like a mule. Is this likely to be caused by the VIS valve problem I've read about? If it is a possible cause, then is there anything I can do to confirm this without having to actually break open the VIS valve as per the instruction I've seen in the 'How To' section? Any ideas.:confused:

Not easily, the best thing to do is dismantle the motor and rotate the gears by hand then conect back to car and turn on the ignition it should move to one of the stops

If you have access to a dealer with Testbook then you can watch it being operated as there is a Test which moves it end to end 4 times

If you are suspicious it is faulty then take the motor apart and check the switches are still soldered in without any breaks around the joints